522 SUMMARY OF CURKENT RESEARCHES RELATING TO 



Some have only one muscle, running from the stigma to the in- 

 tegument, and these may be again subdivided according to the presence 

 or absence of a conical prominence. In others there is but a single 

 muscle, which runs, however, from one angle of the stigma to another, 

 and these may be again subdivided according as they have one cone- 

 like process or two. Then there are some with two muscles for each 

 stigma or even three. 



Structure of Plea minutissima.* — H. Wefelscheid gives an account 

 of this very minute widely distributed water-boatman. He deals in 

 particular with the respiratory and sensory systems, and with the life- 

 history and habits. 



Static Sense-organs in Nepidse.t— W. Baunacke has made an 

 elaborate study of the minute structure, development, and function of 

 the static sense-organs of Ne'pa cinerea and related forms. Three paii's 

 of " sieve-like stigmata " occur on the abdomen of mature Nepidffi. An 

 investigation of their structure shows that they are not breathing organs 

 nor auditory organs nor vestigial structures, but are specially adapted 

 sense-organs which serve for the orientation of the insects when creeping 

 under water. In the larva their place is taken by eight sensory pits, 

 the first of which disappears in the imago. The organs dealt with are 

 complex in fine detail, but they are essentially referable to sensitive setie 

 and a modification of trachese. 



Glands of Cochineal Insects.^ — G. Teodoro describes the minute 

 structure of the lac-glauds and wax-glands in Lecanmm olese. He dis- 

 tinguishes various sets, dorsal, perianal, ventral, anal, stigmal, perivulval, 

 etc. The lac always contains some wax, and the wax some lac. 



Head-glands of Orthoptera.§— S. Suslov has made a study of the 

 minute structui-e and homologies of the head-glands in Dermaptera, 

 Blattodea, and Mantodea. The mandibular glands are homologous with 

 the anterior salivary glands of Machi] is iind Ctenolepisma. The posterior 

 parts of the salivary glands in these last-mentioned types are comparable 

 to the salivary glands of Orthoptera ; both belong to the sixth or labial 

 somite of the head. The head-glands of Orthoptera arise as diverticula 

 of the skin where the fourth somite adjoins the fifth ; they have no 

 excretory function ; they are not nephridial ; they may perhaps be 

 regarded as crural gkmds. 



Embryonic Differentiation of Termite Castes. ||—E. Bugnion has 

 made some observations on this interesting question. He cannot accept 

 the theory of Grassi -that the individuals whidi have Trichonymphid 

 Infusorians parasitic in their intestine undergo "parasitic castration" 

 and become workers or soldiers ; and that those which receive a special 

 salivary diet are freed from Trichonymphid parasites and Ijecome sexual. 



* Zool. Jabrb., xxxii. (1912) pp. 389-474 (2 pis. and 11 figs.). 



t Zool. Jahrb., xxxiv. (1912) pp. 179-346 (4 pis. and 12 figs.). 



t Redia, viii. (1912) pp. 312-20 (2 figs.). 



§ Zool. Jabrb., xxxiv. (1912) pp.' 97-120 (3 pis.). 



II C.R. Soc. Biol. Paris, Ixxii. (1912) pp. 1091-4. 



