Apet´alous, a botanical term applied to flowers or flowering-plants which are destitute of petals or corolla.
Aphanip´tera, an order of wingless insects, composed of the different species of fleas. See Flea.
Apha´sia (Gr. a, not, and phasis, speaking), in pathology, a symptom of certain morbid conditions of the nervous system, in which the patient loses the power of expressing ideas by means of words, or loses the appropriate use of words, the vocal organs the while remaining intact and the intelligence sound. There is sometimes an entire loss of words as connected with ideas, and sometimes only the loss of a few. In one form of the disease, called aphemia, the
patient can think and write, but cannot speak; in another, called agraphia, he can think and speak, but cannot express his ideas in writing. In a great majority of cases, where post-mortem examinations have been made, morbid changes have been found in the left frontal convolution of the brain.
Aphe´lion (Gr. apo, from, and hēlios, the sun), that point of the orbit of the earth or any other planet which is remotest from the sun.
Aphe´mia. See Aphasia.
Aphides (af´i-dēz). See Aphis.
Cabbage-leaf Plant-louse (Aphis brassicæ)—1, 2. Male, natural size and magnified. 3, 4, Female, natural size and magnified.
Aphis, a genus of insects (called plant-lice) of the ord. Hemiptera, the type of the family Aphĭdēs. The species are very numerous and destructive. The A. rosæ lives on the rose; the A. fabæ on the bean; the A. humŭli is injurious to the hop, the A. granaria to cereals, and A. lanigĕra or woolly aphis equally so to apple trees. The aphides are furnished with an inflected beak, and feelers longer than the thorax. In the same species some individuals have four erect wings and others are entirely without wings. The feet are of the ambulatory kind, and the abdomen usually ends in two horn-like tubes, from which is ejected the substance called honey-dew, a favourite food of ants. (See Ant.) The aphides illustrate parthenogenesis; hermaphrodite forms produced from eggs produce viviparous wingless forms, which again produce others like themselves, and thus multiply during summer, one individual giving rise to millions. Winged sexual forms appear late in autumn, the females of which, being impregnated by the males, produce eggs.