170 DIVISION II. COURSE OF DEVELOPMENT OF FUNGI. 



among these algal forms is a fact which separates them at present from the 

 Chytridieae. At the same time the first view is not one which can be entirely set 

 aside ; we are not sure, as has been said already, that phenomena do not occur in the 

 Chytridieae which are at least very near akin to the conjugation of swarm-cells, 

 namely, the supposed conjugation of the young plants just formed from swarm-cells, 

 which have made their way into cells of the host. But if the simple Chytridieae are 

 really related to the Protococcaceae and form a natural series of affinities with all the 

 rest, this series linking with the Protococcaceae must also extend to Polyphagus 

 and the Ancylisteae and Mucorini. 



At the foundation of all such considerations lies the supposition, that the four 

 diiferent groups of the Chytridieae really form a genetic series. This supposition 

 is usual and admissible, but is not necessary. There may quite as well be two 

 or even more than two series before us of separate affinities connected together 

 by certain similarities of adaptation ; on one side the Olpidieae and Synchytrieae 

 without mycelia, and on the other side the Rhizidieae with Cladochytrium ; the latter 

 would unite with the Mucorini or Ancylisteae and could be derived phylogenetically 

 from them ; the former would come from other forms, for instance the Protococcaceae. 

 These questions and considerations cannot lead at present to any certain decision, 

 they can only point out the direction for further enquiries. 



SECTION LII. Doubtful Chytridieae. i. Along with the above-mentioned Zy- 

 gochytrium Sorokin 1 describes a Tetrachytrium triceps, which forms four swarm- 

 cells in each sporangium ; the swarm-cells conjugate in pairs after their escape from 

 the sporangium, then round themselves off and germinate. Before conjugation they 

 resemble those of the Chytridieae. Those which have not conjugated are incapable 

 of germination. Germination gives rise to a small sporangiferous plant, which is 

 attached by a short rhizoid-process to the substratum (vegetable substances decaying 

 in water), and consists of a tube-like cell with four branches formed by bifurcation, 

 three of which terminate in a sporangium and the fourth is sterile, having the form 

 of a horn-like process. 



2. The same observer 2 found on submerged rotten wood in Venice a plant, 

 Haplocystis mirabilis, consisting of a pear-shaped cell, about no n in diameter, the 

 protoplasm of which divides by successive bipartitions into 32 parts; the parts round 

 themselves off, and conjugate in pairs after rotating inside the mother-cell. Then the 

 cell opens by a lid and the products of conjugation issue from it in the form of swarm- 

 cells provided with two cilia ; these cells come to rest in about a quarter of an hour and 

 develope into a cell like the mother-cell. These two remarkable accounts have still 

 to be confirmed. If they are correct, we have to do with organisms which can 

 scarcely belong to the Chytridieae, but must be related to the Protococcaceae. 



There are other and probably many forms of similar habit to the Chytridieae, 

 some of which are very imperfectly known, while others would seem to be certainly 

 distinct from the Chytridieae, but not referable at present to any other group. We 

 cannot go further into the subject of these forms in this place; reference to 

 some accounts of them will be found in Schenk, Algol. Mittheilungen (Amoebidium 

 parasiticum, see below), and Cienkowski, Bot. Ztg. 1861, p. 169. 



1 Bot. Ztg. 1874, p. 308. 2 According to Just's Jahresbericht, 1875, p. 190. 



