138 THE PHENOMENON OF 



the coat of the mother-cell. The mierogonidia, on the 

 other hand, distinguished not only by their smaller size 

 but by a longer shape, a small parietal red vesicle and 

 four long cilia (which appear to be very short in the net 

 forming macrogonidia), swarm out from the bursting 

 mother-cells, move about very actively, often for the 

 space of three hours, and after coming to rest, become 

 green Protococcus-like globules, which vegetate for some 

 time and at length die away without any further pro- 

 pagation. Thus we see here formed in previously 

 indistinguishable sister-cells of the same net, brood-cells 

 of two kinds, which are both direct germ-cells or gonidia, 

 but are developed one into a fertile generation, the other 

 into a sterile generation fated to destruction ; both active, 

 but in different degrees, one, moving for a short time, 

 forming a net, the others, " swarmers," never reunited 

 into a colony.* Two kinds of active germ-cells, (macro- 

 gonidia and microgonidia, occur also in C/ilamidococcus 

 pluvialis (Htematococcus pluvialis, Flotowf) a plant allied 

 to Chlamidomonas and the Volvocineae, into the compli- 

 cated history of which, however, I cannot enter further 

 here, lest I should be led away too far into the debateable 

 ground between the Animal and Vegetable kingdoms. 

 Another example, belonging to the group of the filiform 

 and branched fresh-water Alga3, is furnished by Drapar- 

 naldia, from which Stigeodonium is scarcely generically 

 distinct. Draparnaldia mutabilis, the numerous species 

 of Stigeoclonium, as well as the very nearly related 

 Chatophorce, are among those plants in which the for- 

 mation and birth of active germ-cells may be most 

 easily observed, and indeed have very frequently been 



* I must reserve the history of this remarkable plant, to which I shall 

 return several times, for another opportunity. My own observations were 

 chiefly made in the summer of 1846, and the results made known at the 

 meeting of the Swiss " Naturforschende Gesellschaft," at Schaffhausen, in 

 August, 1847. 



* 'Nova Act. Nat. Cur.,' vol. xx, ii, 1844. (Also Colin, 'Nova Acta,' 

 xxii, p. 397, an abstract of which paper is included in this volume. Also 

 Schacht, ' Die Pflanzcuzclle,' Berlin, 1852, p. 124. A. H.) 



