44 SUMMARY OF CIJKRENT RESEARCHES RELATING TO 



into which it is injected. The serum of dogfish, skate, and torpedo is 

 also toxic for gainea-pigs, but not so markedly as that of Murxna, 

 which is extraorilinary. The toxicity of the serum of Mursena is not 

 due to the presence of the poison as such, for the serum loses its 

 toxicity almost entirely at 65°, while the poison resists this. The 

 toxicity is supposed to reside in a molecular structure, sui generis, such 

 that injection into another blood induces a break-down of molecular 

 equilibrium, marked by the appearance of micellar agglomerations and 

 a lowering of the surface tension of the serum of the poisoned animal. 

 It must be understood that, while the toxicity depends on something 

 besides the poison, it is exaggerated by the poison. 



Evolution of Salmonidse.* — Louis Roule admits that the distant 

 ancestors of Salmonidge may have been marine fishes, but argues that 

 Salmon (Salmo salar) and Sea-trout (Salmo trutta) are fresh-water 

 forms which have taken secondarily and partially to the sea where they 

 have a growing period. They are not to be thought of as marine 

 species which have become adapted to fresh-water conditions. 



History of Faunas and its Relation to Sex.f— Edmond Perrier 

 accepts the theory that fresh-waters are peopled from the sea, but calls 

 attention to the frequent return to marine life, e.g. in reptiles. Passage 

 from the sea to fresh-water tends to be followed by disappearance of 

 males, and the assumption of hermaphroditism (usually protandrous) 

 on the part of the females, e.g. in Oligoch^eta, Hirudinea, Limnaiidge. 

 Maleness is always dangerous ; in fresh-water conditions it may be 

 fatal. The disappearance or reduction of males in Tunicates and 

 Cirripedes is noted. Nematodes show all transitions — separate sexes, 

 useless males, hermaphroditism, and parthenogenesis. It is probable 

 that the hermaphrodite marine Opisthobranchs are derived from 

 Pulmonates which in turn were derived from Prosobranchs which left 

 the sea for the fi'esh-waters. From Opisthobranchs returning, via the 

 littoral zone, to open sea life, the likewise hermaphrodite Pteropods are 

 derived. 



Measurements of Degrees of Kinship.^ — Raymond Pearl adds to 

 his previous studies of inbreeding a re-definition of the fundamental 

 concepts involved. On the basis of these definitions he proposes a new 

 and more accurate method of measuring, and expressing numerically, 

 the degree of kinship between any two individuals whatsoever whose 

 pedigrees are known. A new constant, the partial inbreeding index, is 

 described. Its purpose is to indicate numerically the part of the total 

 inbreeding exhibited in the pedigree of any individual which is due to 

 relationship between the sire and the dam of that individual. 



* Comptes Rendus, clxv. (1917) pp. 721-3. 

 t Comptes Rendus, clxv. (1917) pp. 74S-51. 

 : Amer. Nat., li. (1917) pp. 545-59. 



