620 RECOKD OF CURRENT RESEARCBTES RELATING TO 



cuticular, not cellular, and that they probably contain no living 

 protoplasm through which sensations of taste could be transmitted ; 

 further, the characteristic " taste-cells " are wanting ; and this hypo- 

 thesis fails to explain the presence of the teeth and radial plates. 

 Tactile organs, however, as is the case with the hairs fx'om which they 

 are derived, they might in part be, transmitting to the insect infor- 

 mation as to the absence or presence of free honey in any calyx which 

 is investigated. 



Generative Glands and Sexual Products in Bombyx mori.* — 

 A. Tichomirow has made out a distinct central orifice in the 

 epithelial septum which divides the ovarian ovum from the yolk- 

 chamber; through this a granular substance resembling that of the 

 ■yolk-forming cells is seen to pour into the yolk. The chambers in 

 which the eggs are found after leaving the yolk-forming cells are 

 clothed all over by closely packed epithelial cells between which no 

 spaces occur. Sections show that the epithelium of the yolk-chambers 

 grows thinner as the cells lining the " egg-chambers " grow vertically 

 thicker, these latter form the chorion, each contributing a small plate 

 to it ; in far advanced chambers these plates form a continuous 

 cuticle. 



The terminal spaces of the ovarian tubes are filled with cells, 

 those near the external membrane small, ultimately becoming the 

 epithelium of the tube, the more central ones are successively larger 

 and become ova and yolk-forming cells. Free nuclei occur in the 

 very last chamber, becoming the nuclei of the epithelium. The ovum 

 and the yolk-cells both increase in size, but the former the quickest 

 and chiefly at the expense of the latter. The testes consist of two 

 sacs penetrated by largely branched tracheae ; they contain large 

 numbers of smaller follicles which vary immensely in their shape and 

 the nature of their contents from the youngest, which are spherical, to 

 pear-shaped, and finally to very elongated forms ; in them all, until the 

 spermatozoa are mature, a fragile tunica propria is discernible. The 

 testis is enveloped at the proximal end by a fine connective tissue 

 containing fat-cells ; at the free end the youngest follicles occur, 

 further down riper ones are found, and finally bunches and single 

 specimens of spermatozoids. The penetration of the tracheae into 

 the cavity shows that it cannot be lined internally by an epithelium. 

 In a comparison of the structures of the male and female glands, the wall 

 of the testis corresponds to the common envelope of the ovarian tube, 

 but the ovarian tubes are represented by nothing in the testes ; the 

 follicles in the latter represent the egg-chambers. The follicles with 

 their contained spermatoblasts are to be regarded as only a part of 

 the contents of the gland ; the latter commence as round cells pro- 

 vided with a nucleus and nucleolus, the outline of the nucleus 

 disappears suddenly and a strongly refringent body appears near it ; 

 the nucleolus persists when the cell has taken the form of an 

 elongated fibre ; the subsequent formation of sj)ermatozoa follows the 

 process described by Biitschli. 



* 'Zool. Anzeig.; iii. (18S0) p. 235. 



