Footnotes for Appendices for Essay V.
[199]. Appendix to page [257].
[200]. l. c., p. 118.
[201]. l. c., p. 118.
[202]. Appendix to page [258].
[203]. l. c., p. 137.
[204]. Compare Brücke, ‘Farbenwechsel des Chamäleon.’ Wien. Sitzber. 1851. Also Leydig, ‘Die in Deutschland lebenden Saurier,’ 1872.
[205]. ‘Philosophical Transactions,’ vol. cxlviii. 1858, pp. 627-644.
[206]. Adler, ‘Beiträge zur Naturgeschichte der Cynipiden,’ Deutsche entom. Zeitschr. XXI., 1877, p. 209; and by the same author, ‘Ueber den Generationswechsel der Eichen-Gallwespen,’ Zeitschr. f. wiss. Zool., Bd. XXXV. 1880, p. 151.
[207]. Beyerinck, ‘Beobachtungen über die ersten Entwicklungsphasen einiger Cynipidengallen,’ Verhandl. d. Amsterd. Akad. d. Wiss. Bd. XXII. 1883.
[208]. l. c., p. 144.
[209]. [It is now known that many such caterpillars are actually modified in colour by their surroundings, but the process appears to be indirect and secondarily acquired by the operation of natural selection, like that of the change of colour in the chamaeleon, frogs, fish, etc.; although the stimulus of light acts upon the eyes of the latter animals and upon the skin of the caterpillar. See the seventh Essay (pp. 394-397) for a more detailed account.—E. B. P.]
[210]. l. c., p. 150.
[211]. In order to make the case as simple as possible, I assume that the insectivorous bird feeds upon a single species of insect, and that the insect is only attacked by a single species of bird.
[212]. English Edition, translated by D’Arcy W. Thompson, B.A. London, 1883, p. 509 et seqq.
[213]. Appendix to page [260].
[214]. Ch. Darwin, ‘On the fertilization of Orchids by Insects.’ London, 1877.
[215]. Compare Hermann Müller, ‘Die Befruchtung der Blumen durch Insekten und die gegenseitigen Anpassungen beider.’ Leipzig, 1873. See also many articles by the same author in ‘Kosmos,’ and other periodicals. These later articles are included in the English translation by D’Arcy W. Thompson.
[216]. ‘Lectures on the Physiology of Plants,’ translated by H. Marshall Ward, Oxford, 1887, p. 47.
[217]. Appendix to page [267].
[218]. Brown-Séquard, ‘Researches on epilepsy; its artificial production in animals and its etiology, nature, and treatment.’ Boston, 1857. Also various papers by the same author in ‘Journal de physiologie de l’homme,’ Tome I and III, 1858, 1860, and in ‘Archives de physiologie normale et pathologique,’ Tome I-IV, 1868-1872.
[219]. ‘Oesterreichische medicinische Jahrbücher.’ Jahrgang, 1875, p. 179.
[220]. A direct transmission of the germs of disease through the reproductive cells has lately been rendered probable in the case of tuberculosis, for the bacilli have been found in tubercles in the lungs of an eight-months’ fœtal calf, the mother being affected at the time with acute tuberculosis. However it is not impossible that infection may have arisen through the placenta. See ‘Fortschritte der Medicin,’ Bd. III, 1885, p. 198.
[221]. Compare Unvericht, ‘Experimentelle und klinische Untersuchungen über die Epilepsie.’ Berlin, 1883. With regard to the question of hereditary transmission, the part of the brain in which the epileptic centre is placed is of no importance.
[222]. Compare Ziemssen’s Handbuch der spec. Pathologie und Therapie.’ Bd. XII. 2. Hälfte; Artikel ‘Epilepsie und Eklampsie.’ Leipzig, 1877.
[223]. l. c., p. 269.
[224]. It is generally known that the earlier physiologists believed in what was called the ‘evolutionary theory,’ or the ‘theory of preformation.’ This assumes that the germ contains, in a minute form, the whole of the fully-developed animal. All the parts of the adult are preformed in the germ, and development only consists in the growth of these parts and their more perfect arrangement. This theory was generally accepted until the middle of the last century, when Kaspar Friedrich Wolff brought forward the theory of ‘epigenesis,’ which since that time has been the dominant one. This assumes that no special parts of the germ are preformations of certain parts of the fully-developed animal, and that these latter arise by a series of changes in the germ, which gradually gives rise to them. In modern times the theory of preformation has been revived in a less crude form, as is shown by the ideas of Nägeli, and by Darwin’s ‘pangenesis.’—A. W., 1888.
[225]. Nägeli, l. c. p. 110.
[226]. See Darwin, ‘The Variation of Animals and Plants under Domestication.’ 1875. Vol. I. p. 311.
[227]. Appendix to page [290].
[228]. Weismann, ‘Naturgeschichte der Daphnoiden,’ Zeitschrift f. wiss. Zool. XXIII. 1879.
[229]. Appendix to page [277].
[230]. Compare W. K. Brooks, ‘The Law of Heredity, a Study of the Cause of Variation, and the Origin of living Organisms.’ Baltimore, 1883.
[231]. l. c., p. 82.
[232]. This seems to be the general opinion (see the quotation from Huxley in Brooks’ ‘Heredity,’ p. 127); but I rather doubt whether there is such a constant difference between mules and hinnies. Furthermore, I cannot accept the opinion that mules always resemble the ass more than the horse. I have seen many mules which bore a much stronger likeness to the latter. I believe that it is at present impossible to decide whether there is a constant difference between mules and hinnies, because the latter are very rarely seen, and because mules are extremely variable. I attempted to decide the question last winter by a careful study of the Italian mules, but I could not come across a single hinny. These hybrids are very rarely produced, because it is believed that they are extremely obstinate and bad-tempered. I afterwards saw two true hinnies at Professor Kühn’s Agricultural Institute at Halle. These hinnies by no means answered to the popular opinion, for they were quite tractable and good-tempered. They looked rather more like horses than asses, although they resembled the latter in size. In this case it was quite certain that one parent was a stallion and the other a female ass.—A. W. 1889.
[233]. Darwin, ‘Variation of Animals and Plants under Domestication,’ 1875, Vol. II. p. 41.
ON THE NUMBER OF POLAR BODIES AND
THEIR SIGNIFICANCE IN HEREDITY.
1887.