Group 3. Sera agglutinate corpuscles of Groups 1, 2.
Corpuscles agglutinated by sera of Groups 2, 4.

Group 4. Sera agglutinate corpuscles of Groups 1, 2, 3.
Corpuscles agglutinated by no serum.

The relative frequency of the four groups follows from the following figures. Of one hundred bloods tested by Moss in series of twenty there were found:

10 belonging to Group 1.
40 belonging to Group 2.
7 belonging to Group 3.
43 belonging to Group 4.

Groups 2 and 4 are in the majority and in overwhelming numbers, which indicates that, as a rule, the sera agglutinate the blood corpuscles of individuals of the other groups, but not those of individuals belonging to the same group. The phenomenon that a serum agglutinates no corpuscles (Group 1), or that the corpuscles are agglutinated by no serum (Group 4), are the excep­tions. It is obvious that, as far as our problem is concerned, only Groups 2 and 3 are to be considered. There is no Mendelian character which refers only to one half of the individuals except sex. Since nothing is said about a rela­tion of Groups 2 and 3 to sex such a rela­tion probably does not exist.

8. The facts thus far reported imply the sugges­tion that the heredity of the genus is determined by proteins of a definite constitu­tion differing from the proteins of other genera. This constitu­tion of the proteins would therefore be responsible for the genus heredity. The different species of a genus have all the same genus proteins, but the proteins of each species of the same genus are apparently different again in chemical constitu­tion and hence may give rise to the specific biological or immunity reac­tions.

We may consider it as established by the work of McClung, Sutton, E. B. Wilson, Miss Stevens, Morgan, and many others, that the chromo­somes are the carriers of the Mendelian characters. These chromo­somes occur in the nucleus of the egg and in the head of the sperm. Now the latter consists, in certain fish, of lipoids and a combina­tion of nucleinic acid and protamine or histone, the latter a non-coagulable protein, more resembling a split product of one of the larger coagulable proteins.

A. E. Taylor[57] found that if the spermatozoa of the salmon are injected into a rabbit, the blood of the animal acquires the power of causing cytolysis of salmon spermatozoa. When, however, the isolated protamines or nucleinic acid or the lipoids prepared from the same sperm were injected into a rabbit no results of this kind were observed. H. G. Wells more recently tested the relative efficiency of the constituents of the testes of the cod (which in addi­tion to the constituents of the sperm contained the proteins of the testicle). From the testicle he prepared a histone (the protein body of the sperm nucleus), a sodium nucleinate, and from the sperm-free aqueous extract of the testicles a protein resembling albumin was separated by precipita­tion.[58]

The albumin behaved like ordinary serum albumin or egg albumin, producing typical and fatal anaphylactic reac­tions and being specific when tried against mammalian sera. The nucleinate did not produce any reac­tions when guinea-pigs were given small sensitizing and larger intoxicating doses (0.1 gm.) in a three weeks’ interval; a result to be expected, since no protein is present in the prepara­tion. The histone was so toxic that its anaphylactic properties could not be studied.