THE SNOW-PLANT. 137 



(<?, e 1 ) is as pointed, transparent, and clear as in the later stages, 

 but the nucleus (, n l ) is as yet quite dark. This teaches us 

 that the changes do not go on with similar steps in each individ- 

 ual, but yet all tend toward one end, which we find illustrated 

 here (fig. 76). Each spore has developed, from the transpar- 

 ent end, (e, e 1 ,) a pair of thread-like bodies, (/, /,) of equal 

 thickness throughout, which are in constant motion, writhing 

 and lashing about as far as the increased size of the parent-cell 

 (c) will allow. Plunging now with the microscopic probe within 

 the green mass, we find its interior to be still more largely occu- 

 pied by a transparent space (e 2 ) than in the first change (fig. 74, 

 e) which we took note of; and moreover it is evident that this 

 transparency is in direct continuation with the clear area at the 

 pointed end, (fig. 76, <?, e 1 ,) where the vibratory lashes (/) are 

 attached. In this condition the spores are set free by the burst- 

 ing or dissolving away of the parent-cell (c), and allowed to 

 swim off through less restricted habitats than they have hereto- 

 fore occupied. There is no definite aim to these movements, 

 but each spore seems to lead a sort of indeterminate, roving life, 

 following in an irregular line the lead of the constantly twirling 

 double lashes. 



In process of time there appears a thin, transparent film (fig. 

 77, c) on the surface of the ever-active spore ; at first it is very 

 indistinct, and the outline is indefinite, more like a halo than a 

 sharp, light contour, but gradually it assumes greater prominence 

 and apparent solidity, (fig. 78, c,) and finally it stands off from 

 the surface of the green contents, a firm, clear, sharply defined 

 wall, (fig. 79, c,) with all the characteristics of that of the par- 

 ent, excepting thickness. There is at the same time another 

 equally significant phenomenon of growth that appears during 

 the formation of the spore-wall. Within the granular mass a 

 faint spot (fig. 77, n) looms out of the darkness, and, gradually 

 growing more intense and bright, becomes quite conspicuous ; 

 then it elongates (fig. 78, n) and assumes an oblong form with a 

 constricted middle ; and lastly it undergoes the process of self- 

 division, and the two resultants (fig. 79, n, n) become the most 



