148 A. H. REGINALD BTILT,RK. 



of this paper to show that such sweeping- generalisations with 

 regard to animals are so far entirely without experimental 

 justification. 



With mosses, ferns, etc., there is as yet no proof that the 

 eggs attract the spermatozoa to them in the manner in which 

 Wilson, Verworn, and others believe to be the case with 

 animals. As was pointed out, the eggs of these plants are 

 fertilised in their place of origin. This permits of the 

 surrounding cells, neck-canal-cells, and ventral canal-cell 

 taking upon themselves the function of chemically attracting^ 

 the male sexual element to the female. The eggs may not 

 do more than simply retain the spermatozoa after contact has 

 taken place. Since the eggs of animals are fertilised after 

 liberation from their place of origin, there is no chance of 

 such a division of labour as occurs with plants. In the 

 analogy made by zoologists between ferns and aniiiials there 

 is thus a weak point. Credit is given to the reproductive 

 egg of animals for an excretory function, which has not been 

 demonstrated in the case of plants. 



There is one group of Alga3 — the Fucaceas — which are 

 unique among plants in that their eggs, like those of the 

 Echinoidea, are fertilised after extrusion into water. The 

 eggs of the Fucaceas differ, however, from those of most 

 animals, in being perfectly naked during fertilisation, and 

 in containing chlorophyll which assimilates" in the light. 

 ' Tiie iieck-caual-cells and ventral canal-cell secrete in llie cell-sap ol their 

 vacuoles an attractive substance or .substances (probably a salt or salts of 

 malic acid). Wlieu the archegoniuni bursts these cells burst too, and die, 

 thus liberaling their cell-sap, which dilTuses slowly out of, and from, the 

 moutli of the archegonial tube. Pfelfer, loc. cit. 



- This fact 1 was able to prove by means of Engelmanirs method, usinjr, 

 however, tiie speruKitozoa of a sea-urchin instead of bacteria. A vast numijcr 

 of spermatozoa were added to a pre|)anition containin<r a few ei,'i;s of 

 Cystocyra barbata (one of the Fucacea;). The spermatozoa not in llie 

 neij;hbourhood of the ci.'i,'s came to rest in live minutes. Tliosc around the 

 cgtjs continued in motion for more than an hour. The movement also look 

 place around non-nucleated frMginents of eggs. When the light was cut off 

 from the eggs the movement (juickly ceased, to return again when light was 

 ouce more admitted. 



