ARCHER, ON DESMID1ACE.E. 227 



are figured within and external to an empty Closterium ; these 

 bodies, named by him Bodo viridis, and classed amongst the 

 Infusorial (" polygastric") animalcules. Near the centre of 

 the figure, within the nearly empty frond of the Closterium, 

 there is a green, irregular, rugged mass. Could this be a 

 portion of the granular endochrome untransformed into 

 "zoospores" — his animals of the species "Bodo viridis" ? 



Having thus endeavoured to convey what I believe is 

 the state of the question as to the occurrence of zoospores in 

 the family Desmidiacese, I Avill next draw attention to the 

 accompanying figures (Plate XI, Figs. 1,4). Docidium Ehren- 

 bergii here affords us an example of the production of a 

 few comparatively large ciliated bodies formed at the expense 

 of the cell-contents of the parent cell, and which make their 

 exit therefrom through one or more specially formed lateral 

 tubes. These bodies, although I am quite ignorant of their 

 after development, I cannot but believe to be zoospores ; and 

 I imagine I am justified in the conclusion, their appearance 

 and mode of formation seems to be so comparable to the 

 zoospores in Cladophora, where they undoubtedly, as is well 

 known in this as in variotis other algae, propagate the plant 

 and form young colonies in abundance. The first indication 

 of the commencement of the phenomenon is the production 

 of a single minute hyaline lateral tubercle, or sometimes of 

 two, or more rarely still of three such tubercles, just under 

 the inflation at the base of, I imagine, the younger segment 

 (Fig. 1). This tubercle arises — and the same holds when 

 there are two or three — not from any part of the original 

 segments, but from a special extension of the boundary wall 

 interposed between the inflated base of the segment and the 

 sutural line. In other words, the tubercle is not produced 

 between the segments by their separation at the suture, but 

 from an extension or addition at the base to one only of the 

 segments. On looking at the drawings superficially, it might 

 appear that the new growth, with the projecting lateral 

 extension, was a modification of the phenomenon some 

 cases of which were figured and described by me in our Pro- 

 ceedings of last session (Figs. 10 to 15),* here merely 

 differently carried out with a definite end to meet a special 

 exigency. But the case is different here, for in the abnormal 

 growths alluded to (I. c), the new irregular portions were 

 added between the old segments by their separation at the 

 suture, making a third development specially belonging to 

 neither old segment ; whereas here, as I have just indicated, 



* 'Nat. Hist. Review,' vol. vi, p. 1-69, Plate xxxiii, figs. 10—15. 



