462 sr.MMAKY 01 I UBBENT RESEARCHES RELATING TO 



attention is directed to the abundance of two interesting Ascoglossans 

 or dose allies of the Nudibranchs, Hermm dendrtitca and Elysva vindts, 

 an d of I 'erithium reticulatum and C.perversum. 



y. Gastropoda. 



Beating of the Heart in Hibernating Snail.*— Arnold Lang has 

 studied this in Helixpomatia, in most cases by making a window in the 

 .shell above the heart and putting in a little pane of glass or the like. 

 \s the temperature falls the number of beats decreases : the two curves 

 are almosl parallel. There was 1 beat per minute at -06° C. ; 2-36 

 at + 2 ■ 65° ; 5 • 7") at 5 ■ 3° ; 8 ■ 26 at 7 • 7° ; and so on. There is a greatly 

 reduced power of reaction as the winter sets in with severity. Yet after 

 persisted low temperature the heart was observed beating slowly at 

 even - 3 C. 



Reduction in the Spermatogenesis of the Snail.t— A. Bolles Lee 

 confirms his previous conclusion that there is a conjugation of chromo- 

 somes in the course of spermatogenesis. It occurs in the auxocyte stage, 

 I nit it remains uncertain whether it is a phase of the process of numerical 

 reduction of chromosomes. 



Abnormality in Snail.t — 6. Q u in taret describes a specimen of Helix 

 aspersa with a supplementary penis which contained spermatophores. A 

 double penis lias been described by Rouzaud in Bidimus detritus and 

 some other forms, but in these there was but oue aperture, whereas in 

 the monstrosity described there are two distinct apertures. There has 

 Wren a longitudinal splitting of the penial primordium. 



8. Lamellibranchiata. 



Influence of Radium on the Development of Pholas Candida. §— Jan 

 Tnr finds that fertilized ova, beginning to develop, were not affected by 

 the influence of radium-bromide as regards segmentation, gastrulation, or 

 the formation of the veliger larva. In the larval stage, however, there 



an to be a degeneration and discharge of superficial epithelial cells. 

 On the other hand, ova exposed to the radio-active influence for 6 to 

 24 hours, before fertilization, showed, instead of the unequal, a perfectly 

 equal segmentation. The gastrulation was none the less by epibole, as 

 usual. 



Notes on Fresh-water Mussels. || — W. Israel points out that two 

 rings are sometimes made in one year. In the Danube the young occur 

 in the gill-chamber in April to June, and also in October to December 

 in Anodonta piscinalis, in October to November in Pseudanodonta com- 

 planata, in May and June in Unio pictorum, in December and January 

 in U. tumidus, and in August in U. consentaneus. 



* Festschrift Richard Hertwig, iii. (1910) pp. 1-14 (5 pis.). 



t La ( lellule, xxvii. (1910) pp. 55-74 (1 pi.). 



j C.R. Soc. Biol., lxx. (1911) pp. 55-56. § Tom. cit., pp. 679-81. 



i ichtsbl. Deutsch. Malakol. Ges., xliii. (1911) pp. 10-17. See also Zool. 

 Zentralbl., xviii. (1911) p. 216. 



