Miscellaneotts. 395 



the proper admstment and correcti9ns, through a sufficient depth of 

 water to completely cover the Actinophrys {A. Eichhornii), and could 

 readily detect the walls, not only of the superficial cells, but also of 

 the innermost ones *. 



What is remarkable, too, the pseudopodia, as frequent and careful 

 observations have led him to determine, invariably alternate with the 

 cells of the exterior layer ; that is, they are prolongations of the in- 

 tercellular amorphous substance of the body. This fact would seem 

 to add to the proof that the so-called vacuoles are really cells ; other- 

 wise it would be hardly credible that simple vacuoles, which come 

 and go in an amorphous substance, should always alternate with the 

 pseudopodia. 



Sometimes a pseudopod moves very rapidly, especially when it has 

 seized upon some victim ; for then it retracts with a sudden jerk, and 

 draws the prey close to the body, which finally engulfs it in the same 

 manner as docs Amoeba. The pseudopodia exhibit an adhesive power 

 which is remarkable when we consider the size of the animals which 

 are sometimes drawn in by them, and in this respect remind one of 

 the "adhesive vesicles" in the anchors of Lticemaria, which hold fast 

 to bodies with the greatest tenacity, and, to all appearances, by simple 

 contact, just as glue and mucus adhere to anything which touches 

 them. [See Prof. Clark's paper "on Lucernaria, the Ccenotype of 

 Acalephse," Proc. Bost. Soc. Nat. Hist. vol. ix. (1862) p. 52, and also 

 reprinted, " with additions and notes," in the ' Annals of Natural His- 

 tory,' July 1863, p. 19.] In a Dijfflugia (very near D. proteiformis). 

 Prof. Clark had observed that whenever the pseudopodia contract, 

 they invariably become strongly wrinkled transversely ; and, as he 

 could not detect the least trace of an envelope or wall like layer on 

 this part of the body, he believed that the wrinkling is peculiar to 

 the substance of the pseudopodia. 



[In connexion with this, I will take the opportunity to assert that, 



* [The unprecedented working distance which accompauies the great 

 angle of aperture in the above-mentioned lens prompts rae to speak more 

 fully of its excellence. It has been the chief desideratum of naturalists to 

 obtain a large increase in the working distance of those lenses which have 

 a great angle of aperture ; but hitherto the latter condition has seemed to 

 involve neoesaahly an excessively short working distance, and consequently 

 great inconvenience in the investigation of all bodies which are not corre- 

 spondingly thin. The idea of studying marine animals in their native 

 element with such lenses could never be indulged in, for fear of ruining 

 the objectives by contact with salt water. At last we are relieved from this 

 restraint ; for w ithin the last four or five years a great improvement has 

 been made in this respect by opticians, at least bv Mr. Tolles. The most 

 recently constructed lens which I have received from that gentleman was 

 inade last June ; it is a one-quarter-inch objective, with an angular aper- 

 ture of (me hundred and fifty decrees, and a most unexj)ected working 

 distance of one-fiftieth of an inch for uncovered bodies. By experiment, 

 I also find that it works through a glass covering fully one-fortieth of an 

 inch thick, and with some room to spare above that. The working distance 

 through water I have not measured accurately ; but that can be inferred 

 from the difference between its refraction and that of gla^ss. The defining 

 power of this lens is certainly unsurpassed, if not unequalled.— H.J. C.J 



