562 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the materia] investigated, the authors find that variation in the laying 



activity is the prime cause of the changes in yellow pigmentation in the 

 domestic fowl. 



Influence of Temperature on Rate of Development of Fishes.* 

 A. C Johansen and A. Krogh have repeated Dannevig's experiments 

 on the influence of temperature on the rate of development of fish eggs, 

 and confirm them in regard to the plaice. The increase in the rate of 

 development with a rise of temperature is proportional to the increase 

 in the temperature. In other words, the curve expressing the relation 

 between temperature and rate is a straight line. It was also shown that 

 a low oxygen pressure has a retarding influence on development. 



Influence of Temperature on Rate of Developments — August 

 Krogh has experimented with the eggs of frogs, fishes, and water- 

 beetles, and has obtained data as to rates of segmentation of the eggs 

 of sea-urchins, in order to find out how far they illustrate van't Hoff's 

 formula. He finds that the relation between the temperature and the 

 rate of development cannot be expressed, even approximately, by 

 van't Hoff's formula. In the cases tested the relation is algebraic over 

 a range of temperatures which corresponds approximately to that at 

 which normal development can take place, and the curve representing 

 the relation is consequently a straight line. 



Larval Polypterus.^ — F. Gkiitel has made a study of a larval stage 

 of Polypterus senegalus, 59 mm. in length,.said to have come from Lake 

 Tchad. He describes the fin-rays, the scales, the pores of the lateral 

 line. On the head there are 17 pores in the preopercular-mandibular 

 series, 12 in the two supra-orbital series, 2G in the two infra-orbital 

 series, 3 in the supra-temporal series, 58 altogether. The minute struc- 

 ture of the scales is discussed, and the kidneys are briefly described. 



Peristomal Mesoderm and Tail in Lamprey. § — S. Hatta describes 

 the origin of the peristomal mesoderm in Lampetra mitsulcurii, a Japanese 

 lamprey. The outer and inner layers roofing over the archenteron in 

 front of the dorsal blastoporic lip are added to by the posterior growth 

 of the dorsal and lateral lips, by Avhich the blastopore is reduced. During 

 the reduction of the blastopore, in the inner layer which passes round 

 the blastoporic lips into the outer layer, there can always be distinguished 

 three divisions : the median stem in front of the dorsal blastoporic lip 

 and two limbs behind it, the latter constituting what is known as the 

 peristomal mesoderm. 



Before the blastopore is completely closed, the hindmost part of the 

 peristomal mesoderm undergoes peculiar changes. The outer layer of 

 the ventral blastoporic lip, the ectoderm, sinks in and forms a short 

 median, longitudinal slit, the proctodeum. The invaginated procto- 

 deum divides the peristomal mesoderm into two tail wings or lobes 



* Publications de Circonstance, No. 68, Conseil Internat. pour l'Explor. ds la 

 Mer, Copenhagen, 1914, pp. 1-44 (14 figs.). 



t Zeitschr. allg. Physiol., xvi. (1914) pp. 163-77 (8 figs.). 



: Arch. Zool. Exper., liv. (1914) pp. 411-37 (2 pis. and 12 figs.). 



§ Annot. Zool. Japon., ix. (1915) pp. 49-62 (3 figs.). 



