ZOOLOGY AND BOTANY, .MICROSCOPY, ETC 539 



Faceted Eyes of Libellulids, etc.* — K. Zimmermann has made a 

 comparative study of the eyes of Libellulids, Phasmids, and Mantids. 

 In all the forms examined he finds that the chief pigment-cells and 

 the corneagen cells are homologous structures Continuations of the 

 chief pigment-cells reach right up to the cornea ; the small triangular 

 interpolated pieces between the cornea and the nuclei of the circular 

 cells belong to the chief pigment-cells. In those Libellulids in which 

 the eye is divided by difference of pigmentation into two regions, it is 

 only the darkly pigmented latero-ventral portion which functions during 

 the larval stage. The retinula is originally made up of eight cells, of 

 which one usually becomes rudimentary. Usually only tbe nuclei of the 

 eight cells are demonstrable, but in Sipyloidea the remains of a cell-body 

 can be seen. The Mantid eye possesses an iris-tapetum. 



Spinning Apparatus of Embiidse.t — M. Eimsky-Korsakow has 

 studied the structure and development of the spinning apparatus which 

 is found in the expanded first tarsal joint of the fore-legs in all species 

 of Embia. There are three kinds of hairs on the under surface of the 

 tarsal joint — ordinary hairs, much smaller spine-like hairs (perhaps 

 moulting-hairs), and hairs through which the ducts of the spinning 

 glands open. Four types of glands are carefully described. The plasma 

 of the glands is used up in forming the secretion. Each efferent duct 

 shows a peculiar ampulla which opens into the gland by four oval 

 apertures and also shows several fine hair-like processes. It seems that 

 the spinning process is under voluntary control. The glands which 

 compose the apparatus increase in number as growth goes on : there 

 are 14-15 at hatching ; there may be over a hundred in the adult. 

 The cells which form them are segregated from the hypodermis and are 

 at first amoeboid. They migrate more or less into the interior of the 

 tarsal joint and form a syncytium, whereas in other insects with spinning 

 glands the cell boundaries are distinct. The author indicates that the 

 spinning glands of Embiidas might arise from skin glands like those 

 (unicellular, however) known as Stein's glands. There is also some 

 resemblance between the glands of Embiida? and those in Pantopod 

 larvae and in second antennas of Oniseus rnurarius. 



Copulation and Spermatophores of Gryllidae and Locustidae. :{: 

 Ulrich Gerhardt has published a second paper in which he deals with 

 pairing in many additional types of Gryllidae and Locustidae. The 

 investigator does not find any warrant for referring the process of 

 copulation, still less the structure of the spermatophores in the two 

 families, back to a common form, yet there are many common features 

 that justify certain general conclusions. The primitive position in pair- 

 ing is more consistently maintained among the Gryllidae than among the 

 Locustidae, where there is differentiation of the cerci and of the subgenital 

 plate in the male : thus structural progress has been associated with 

 changes in habit. In regard to the spermatophores, there are three types 

 only comparable in their general features. The sperm-sac in the 



* Zool. Jahrb. Abth. Anat. xxxvi. (1913) pp. 1-36 (2 pis. and 3 figs.). 

 + Zeitschr. wiss. Zool., cviii. (1914) pp. 499-519 (2 pis. and 1 fig.). 

 X Zool. Jahrb. Abth. Syst., xxxvii. (1914) pp. 1-64 (3 pis.). 



