Reproductive Phenomena of the Amoeban Rhizopods. 333 



gitudinal section taken from the free margin of the perianth, 

 the gradational changes which take place in the cytoblast^ from 

 the free state first described to that in which it is embraced by 

 the green chlorophyll- granules, and, after divesting itself of these 

 bodies, becomes difi'erentiated into a distinct anterior and poste- 

 rior portion, the former throwing out the flagelliform proboscis 

 of Astasia, whereas a regularly pulsating contractile vesicle inva- 

 riably occupies a position in the latter, are most strikingly ma- 

 nifested. Of the purely endogenous origin of the Astasia-Vike 

 bodies I feel perfectly satisfied, having, as already stated, not 

 only detected the single cytoblast in every cell both of the leaf, 

 the spiral flower-stem, and the perianth, but also assured my- 

 self by the most careful examination that no lesion had taken 

 place in the cell-walls whereby the entrance of zoospores might 

 have been efi"ected. But the most wonderful feature remains 

 yet to be noticed — namely, the multiplication of the Astasia- 

 iike bodies by longitudinal fission whilst still within the parent 

 cell, until sometimes as many as ten have been congregated 

 together. In several cases the entire process, which did not 

 occupy more than half an hour, took place under my eyes — com- 

 mencing at the ciliated extremity, and proceeding backwards 

 until it reached the contractile vesicle, which, after sundry parti- 

 tions and reunions, finally divided into two halves, one of which 

 was apportioned to each of the new individuals. 



Without entering at present into the subsequent history of 

 these bodies, I am desirous of pointing out wherein they resemble 

 and wherein they present marked differences from the characters 

 described by me as pertaining to Amoeba. Like the Amoeban 

 Rhizopods generally, without any exception, whether naked or 

 testaceous, their protoplasmic substance is differentiated into 

 an anterior and posterior portion. Their contractile vesicle 

 discharges itself invariably in the latter region, but, unlike that 

 of the Amoeba, it is fixed in that position permanently. When 

 supplementary contractile vesicles are given off from or near the 

 primary one, they either coalesce with it or discharge themselves 

 independently as in Amoeba. The nucleus which is in the centre 

 of the body never alters its position. And lastly, whereas the 

 movements in Amoeba are strictly polymorphous, those of the 

 Astasia-like organisms have the power of altering their outline 

 only, by extending and contracting the body round an imaginary 

 axis ; so that although it is conceivable that the reparation of 

 lost parts may take place, such reparation would consist in the 

 renewal of a determinate and not an indeterminate figure. 

 Coupling this, then, with the absence of any digestive apparatus 

 whatever, we are furnished with a clear line of demarcation 

 between the animal and vegetable, whilst in the simpler forms 



