ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



373 



Role of Ganglia in Immobilization. — E. Rabaud {Bull. Soc. Zool. 

 Frame, 1918, 42, 158-66). Experiments made on a Millipede {Lepto- 

 iul'us belqicus), and various insects (Coleoptera, Odonata, Lepidoptera) 

 show that reflex immobilization does not depend exclusively on this or 

 that ganglion. It depends on the nervous system as a whole, its 

 excitability, and its relations with the outer world. But the suppression 

 of particular ganglia means a restriction of a varying number of excita- 

 tions, and this works towards reflex immobilization. In different types 

 corresponding ganglia vary in importance. Thus in insects with big 

 eyes the cerebral ganglia count for much, since the visual stimuli are 

 intensely counteractive of immobilization. In insects with small eyes 

 other areas of stimulation become relatively more important. J. A. T. 



Study of Ant Larvae. — W. M. "Wheeler (Proc. Amer. Phil. Soc, 

 1918, 57, 293-343,12 figs.). Various Ponerine larvae when fed by the 

 workers are turned on their backs, and fragments of insects are placed 

 on their concave ventral surfaces. On these the larva discharges salivary 

 secretion with a strong proteolytic ferment, and part of this is licked up 

 by the nurses. In some other larv» which receive liquid food there 

 are tubercles and other delicate outgrowths from which exudation 

 occurs. There may be fleshy lobes of the labium, or a cluster of 

 tubercles about the head, or a tentacle-like process from the mid- 

 ventral line of the mesothorax. This stage is called by Wheeler the 

 " trophidium." 



Labval Stages of Pachysima ^thiops. 



(A) Ventral and (B) lateral views of first larval stage (" trophidium ") 



of Pachysima lethiops. 



