718 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of A . thomsoniana, from which it appears that the mode for sub-species 

 (ooperce falls exactly between A. thomsoniana proper and sub-species 

 port&ra. 



Gastropod Studies.* — Amadeus Grabau gives an account of the 

 shell development in the genera Fulgur and Lyeotypus, and discusses its 

 bearing on the question of the succession of species in time. A table of 

 genetic relationships of species is given. 



Sexual Differentiation in the Hermaphrodite Gland of Limax 

 maximus. j — P. Ancel comes to an exactly opposite conclusion from 

 M. Babor, regarding the order of appearance of the sexual elements in 

 L. maximus. The sex-cells up to a certain time are indifferent and 

 capable of developing as male or female. The determining factor is the 

 proximity of nutritive cells which arise from the same primitive elements 

 as the sex-cells. These tend to produce ova. Their absence is the indirect 

 cause of particular cells developing as male elements. The order of appear- 

 ance of these three types of cell is such that protogyny is not possible. 



5. Liamellibranchiata. 



Utilisation of Carbonate of Lime by Anodonta.J — Doinet de 

 Vorges communicates the results of an experiment with a young speci- 

 men of the freshwater mussel, Anodonta cggnea, which, though by no 

 means conclusive, tend to show that this bivalve can utilise the carbonate 

 of calcium in the water. It is noteworthy that in this experiment the 

 magnesium salts remained quite constant. 



Rib Variation in Cardium.§ — F.C.Baker has studied this in 

 Cardium robustum (= G. magnum), G. isocardia, and C. muricatum, 

 using several hundred specimens of each species from the same general 

 locality. The fact presents itself, that in each species there is a mode or 

 constant which remains unvaried, and from which certain individuals 

 vary sporadically. It also appears that the number of ribs is not a safe 

 •character upon which to found a species. 



Arthropoda. 

 a. Insecta. 



Insects and Floral Colours. || — John H. Lovell sums up a paper, 

 rich in observational material, in the conclusion, as far as insects are 

 •concerned, that their preferences depend, not on assthetic colour-sense, 

 1 but on association of particular colours with food material. Con- 

 spicuousness, or contrast of the inflorescence with the foliage, may be 

 referred to selection. It is of advantage to the insects, since it enables 

 them to find nectariferous flowers more quickly, and to the plants 

 because it aids in securing cross-fertilisation. Many colours are better 

 than one, since the colours are rendered more conspicuous by contrasts 

 with each other as well as with the foliage, and insects are less liable to 

 visit them indiscriminately. This paper is also referred to under 

 " Botany." 



* Araer. Naturalist, xxxvii. No. 440, pp. 515-39. 



t Arch. Zool. Expe'r., series 4, i. (1903), Notes et Kevue No. 7, pp. cv-cxv. 



% Bull. Soc. Zool. France, xxviii. (1903) pp. 149-50. 



§ Amer. Naturalist, xxxvii. (1903) pp. 481-8 (7 figs.). 



J| Tom.cit., pp. 443-79. 



