ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 295 



cap " appears at the heavy end of the egg. It probably consists of 

 nutritive material. 



When the yolk, grey cap material, and cytoplasm are shifted by 

 centrifugins;, no conspicuous changes result in the formation of the 

 embryo. Even when the yolk is driven entirely to one end, the embryo 

 develops near the opposite, lighter end independently and normally. 

 This suggests the conclusion that the superficial layer of cytoplasm is 

 the controlling substance, and that this cytoplasm is heterogeneous. 



This view is confirmed by observations on the normal development, 

 and by the fact that killing a portion of the cytoplasm with a hot 

 needle results in the absence of the part of the embryo to which this 

 cytoplasm would otherwise have given rise, although no nuclei were 

 destroyed. It is Hegner's conviction that the large features in develop- 

 ment — those of phylum, class and order — are controlled by the hetero- 

 geneous cytoplasm, while smaller characteristics are more under the 

 influence of the chromatin. 



Concealment of Eggs of Potato-beetle.* — R. W. Hegner has made 

 experiments with the eggs of Leptinotarsa decemlineata in order to deter- 

 mine if direct sunlight is injurious to the development. He found that 

 the eggs are not retarded in their development, but that they fail to 

 hatch. The non-hatching is probably due to partial desiccation. The 

 chief use of the concealment is probably to keep the eggs away from 

 the sunlight. 



Flight of Cicada. t — Amans has made an analysis of the flight of 

 Cicada pleheia. He has also shown that Cicadas, like Hymenoptera, 

 can dispense with their hind wings. There is a reduction in the strength 

 and in the capacity for manoeuvres, but the flight remains good and the 

 song is unaifected. 



New Thysanoptera.+ — R. S. Bagnall describes some interesting new 

 forms of these minute insects collected in Trinidad. The new genera, 

 Sedulothrips, Graniothrips, and Ghirothripoides, are established. 



5. Arachnida. 



Genus HaBmaphysalis.§ — G. H. F. Nuttall and C. Warburton, in 

 continuation of a monograph of the Ixodoidea, gave an account of the 

 genus Hsemaphysalis. The members are Metastriata, i.e. with anal 

 grooves embracing the anus posteriorly ; they are usually of small size ; 

 the scutum is inornate and without eyes, and the female without lateral 

 grooves ; the capitulum has a sub-rectangular base ; the palps are 

 normal, short and conical, broadest near the posterior end of article 2, 

 which (except in rare cases) projects laterally beyond the base ; the 



• Psyche, xxii. (1915) pp. 24-7. 



t Bull. Acad. Sci. MontpeUier, Nos. 7-12 (1915) pp. 183-92 (2 figs.). 

 X Journ. Linn. Soc. (Zool.) xxxii. (1915) pp. 495-507 (2 pis.). 

 § A Monograph of the Ixodoidea. Part III. Ixodidse : The Genus Hcema- 

 physalis. 1915, pp. xiii and 202 (144 figs, and 6 pis.). 



