260 ME. p. J. COLE ON" THE DETELOPMENT OF 



extremity of the cell by the ingro"wing cuticle. As I have not 

 investigated the blastogenesis of the rhabdite-" cells,". I am 

 not in a position to express an opinion as to the accuracy of the 

 above statement. I can, however, assert that a true cuticle is 

 not present on the free surface of the rhabdite-battery of the 

 adult, although a peripheral deeply-staining membrane is often 

 seen, but this is not a cuticle. That it would be noticed if 

 present in my sections is shown by the fact that the axis of each 

 branchial plume has a cuticle which is quite obvious, but with 

 one exception, when it was traced on to the base of the battery, 

 this is always seen to stop short of the knob of the battery. 

 Indeed in some sections, which were kindly placed at my disposal 

 by Prof. Howes, indications were not uncommon of a few rows 

 of cells situated external to what I have supposed is the free 

 surface of the battery, i. e. the surface bounded by the supposed 

 cuticle. It is possible these may represent a true epidermis 

 which has been lost by the maceration of the material, although it 

 seems very improbable that it would have been lost in by far 

 the greater majority of the batteries. The existence of such a 

 layer is, however, rendered conceivable by the position frequently 

 assumed jby the immature rhabdite-" cells," and also by the 

 usually ragged and seemingly artificial free border of the enlarge- 

 ments themselves. 



Desceiptiou" of the Ehabdite-" cells." 



The occurrence of the " cells " of the rhabdite-batteries on the 

 branchial stems has been correctly described and figured by 

 Mcintosh, so that it is not necessary to recapitulate it here. A 

 close examination of the rhabdite-" cells " in a number of 

 specimens discloses two important and significant facts : (1) No 

 two "cells" are ever exactly similar — hence they are "cells" in 

 which a great amount of metabolism is going on ; (2) there are 

 two extremes of position — (a) near the basal cells of the battery, 

 and (J) absolutely outside the battery and lying on its surface. 

 These two extremes of position are bridged over by the necessary 

 intermediate stages. These two observations alone justify us in 

 concluding — (1) That the " cells " are engaged, aud actively 

 engaged, in secreting something, and are hence of a sort gland- 

 cells ; (2) that that something is a body which, to serve its 

 purpose, must be cast on to the exterior. Similarly, the observations 

 at once preclude the possibility of the " cells " being sense-organs 



