DE BARY ON FERTILISATION. ^77 



margin of the drop next the window. Here there soon presented itself a sight 

 quite different from the ordinary one. 



' For while I saw the swarmers from one and the same spore evidendy evade 

 one another and distribute themselves at about equal distances apart, there were 

 soon formed numerous copulating groups, if I may so say, i. e. collective groups 

 into which the individual swarmers, so to speak, precipitated themselves head- 

 long. I now saw continually new pairs of united swarmers leaving these 

 copulation-centres. Frequently, also more than two were anchored together. The 

 swarmers as a rule abut on one another with their anterior ends, but at once lay 

 themselves together sideways, and then fusion follows. It begins at or near the 

 apex, and soon extends over the whole side. The cilia remain free and active 

 meanwhile, so that the copulating swarmers go on swarming widi the four cilia, 

 their movement being particularly tumultuous. The swarmers in the pre- 

 viously mentioned cases are directed parallel, but in other and by no means 

 rare cases they are seen to be fused laterally, so that their ciliated ends are turned 

 away from one another. The union may also first take place at the hinder 

 portions of the swarmers, so that they diverge from one another at their anterior 

 ends. Finally, I also saw cases where they were united in a cross-like manner. 

 This however seemed to me to exhaust the variety of cases of pairing. 



' As already mentioned, more than two swarmers may exceptionally fuse 

 with one another. The simplest case here again was that they laid themselves 

 together parallel to one another. They then worked on with six cilia, going 

 forward like simple swarmers. I saw also complexes in which two swarmers 

 took up one direction, and the third the opposite one, and finally also such 

 which owed their origin to a large and often indefinite number of swarmers. I 

 could see from an approximately cuboidal mass a large number of colourless 

 spots project, each moving its pair of cilia. The whole showed an irregular 

 rotating movement. 



' The red streak of the swarmers may assume any position during the 

 copulation. 



' After swarming for some time, in all cases longer than in the case of those 

 swarmers which remain free, each copulation-product rounds itself oft". At first 

 it is possible still to recognise the colourless spots of the copulated swarmers in 

 the complex, and even the cilia may be still retained on the sphere. The colourless 

 spots and cilia then disappear, however, and we have a sphere coloured green 

 with chlorophyll, in which a corresponding number of red streaks are to be 

 distinguished.' 



Sdll more remarkable and astounding than the above statements, which I 

 have expressly taken verbatim from the original memoir, are perhaps De Bary's 

 most recent statements in his ' Untersuchungen über die Perotiosporeen und Sapro- 

 legnieen' (1881), where he devotes a special chapter to the fact, established by 

 himself, that in these Fungi the oogonia are usually the first to develope, the 

 male fertilising tubes not having been present meanwhile : these latter however 

 are developed during a certain stage of development of the oogonium, and ex- 

 clusively in its neighbourhood, either from a branch which belongs to the same 

 shoot as the oogonium, or else on other tubes which are not at all connected 



