CH. VIIl] ANTHEROZOIDS. 199 



side walls of the stellate parenchyma cells, and may even 

 be crowded into the corners. In the shaded leaves they 

 are spread out and dotted over the surfaces which are 

 parallel to the plane of the leaf. The leaves may be pre- 

 served in alcohol for future examination. 



(249) Ghemotaicis : antherozoids. 



The following instructions are taken from Pfeffer's 

 paper in his Untersuchungen^. The prothalli which yield 

 the antherozoids for Pfeffer's experiments were chiefly 

 small ones of Blechnumfraccineum and Adiantum, cuneatum. 

 They were grown on lumps of peat in the shade of other 

 plants and were used when only about a millimeter in 

 length, and had numerous antheridia but few or no 

 archegonia. They should be kept only moderately damp, 

 as this seems to favour the yield of antherozoids. The 

 prothalli having been washed for a moment are placed 3 

 or 4 together under a small cover-glass supported on 

 strips of paper, and are washed by repeatedly drawing a 

 current of rain water through the preparation. Distilled 

 water being injurious to the antherozoids must not be 

 used for the washing, the object of which is to remove any 

 malic acid which may be set free by the rupture or injury 

 of the tissues of the prothallus. The reasons for 

 preferring a small cover-glass are that the antherozoids 

 are thus confined to a smaller space, and that the water is 

 better oxygenated than when a large glass is used. 

 Capillary tubes of O'l to 0'14 mm. internal diameter and 



' Vntermchungen aus dem Botanischen Institut zu Tubingen, i. 1881 — 

 1885, p. 363. 



