670 REPORT— 1901. 



Some years ago Mr. H. M. Vernon, when hybridisin» ecbinoderms, discovered 

 that ' the chai'acterisics of the hybrid offspring depend directly on the relative 

 degrees of maturity of the sexual products.' ^ Mr. Vernon found subsequently 

 that over-ripe (stale) ova fertilised with fresh sperms gave very different results 

 from fresh ova fertilised with over-ripe (stale) sperms, from which he inferred 

 that over-ripeness (staleness) is a very potent cause of variation. '-' 



I find that if a well-matured rabbit doe is prematui-ely {i.e., some time before 

 ovulation is due) mat^d with a buck of a diftereut strain, the young take after the 

 sire; when the fertilisation takes place at the usual time, some of the young- 

 resemble the buck, some the doe, while some presimt new characters or reproduce 

 more or less accurately one or more of the ancestors. AVheu, however, the 

 mating is delaj^ed for about thirty hours beyond the normal time, all the young, 

 as a rule, resemble the doe. It may hence be inferred that in mammals, as 

 in echinoderms, the characters of the offspring are related to tlie condition of 

 the germ-cells at the moment of conjugation, the offspring resulting from the 

 union of equally ripe germ-cells differing from the offspring developed from the 

 conjugation of ripe and unripe germ-cells, and still more from the union of fresli 

 and over-ripe germ-cells. This conclusion may be said to be in harmony with 

 the view expressed by Darwin, that the causes which induce variability probably 

 act ' on the sex elements before impregnation has been effected.' ^ The results 

 already obtained, though far from answering the question why theie is often 

 great dissimilarity between members of the same family, may lead to further 

 experiment, and especially to more complete records being kept by breeders. It 

 is unnecessary to point out what a gain it would be were breeders able to 

 regulate, even to a small extent, the characters of the offspring. 



Is the Condition of the Soma a Cmise of Variation 1 



There is a considerable amount of evidence in support of the view that 

 changes in any part of the body or soma which affect the general welfare 

 influence the germ-cells. This is but what might be expected if the soma in 

 the metazoa is to the germ-cells what the immediate surroundings are to the 

 protozoa. The soma from the first forms a convenient nidus for the germ-cells, 

 and, wlien .sufficiently old and sufficiently nourished, it provides the stimuli by 

 which the ripening (maturing) of the germ-cells is effected. If in the case of 

 the protozoa variation is due to the direct action of the environment, it may 

 be inferred that in the metazoa variations of the germ-cells result from the 

 direct action of the soma, i.e., from the direct action on the germ-cells of their 

 immediate environment. This, however, is quite a different thing from saying 

 that definite .somatic variations are incorporated in the germ-cells (converted into 

 germinal variations) and transmitted to the offspring. 



It may first be asked, Does disease, in as far as it reduces the general vigour or 

 interferes with the nutrition of the germ-cells, act as a cause of variation ? 1 

 recently received a number of blue-roclc pigeons from India infected with a blood 

 parasite (Halteridium) not unlike the organism now so generally associated with 

 malaria. In some pigeons the parasites were very few in number, in others they 

 were extremely numerous. The eggs of a pair of these Indian birds with 

 numerous parasites in the blood proved infertile. Eggs from a hen bird with 

 numerous parasites fertilised by a male with few parasites proved fertile, but the 

 young died before ready to leave the nest. An old male Indian bird, however, 

 with comparatively few parasites, mated with a mature half-bred English turbit 

 produced a single bird. The half-bred turbit has reddish wings and shoulders, but 

 is otherwise white. The young bird by the Indian blue-rock is of a reddish 

 colour nearly all over, but in make not unlike the cross-bred turbit lieu. 



Some time before the second pair of eggs were laid, the parasites had com- 

 pletely disappeared from the Indian bird, and he looked as if he had quife 



' Proceedings Royal Society, vol. Ixiii. May 189S. 

 ' Ihid., vol. Ixv. November 1899. 

 ■' AnimaU and Plants, vol. ii. p. 259. 



