I894-J NEW-YORK MICROSCOPICAL SOCIETY. 65 



hyphae. With the formation of each new cell either a branch 

 from the filament encircling the mother cell or from the mycelium 

 is put out to get possession of it. At the moment of union an 

 unmistakable quickening is manifest both in host and parasite. 

 The latter puts out, at a short distance from the alga, from one to 

 several branches that follow the main fibril and encircle the alga 

 in various windings (Fig. i). The alga greatly increases in size, 

 and the early growth often suggests a strong resemblance to the 

 fingers of a hand closing about a ball. The gonidia often attain 

 a diameter of twenty yu, averaging about nine /<, thus exceeding 

 the size of Protococcus viridis Ag. by about two /<. In the more 

 mature thallus the crowding and subsequent distortion give them 

 a somewhat smaller appearance. The activity of the fungal hy- 

 phce was apparently due to the food furnished by the algge. The 

 increase of the algae, however, seemed due rather to some stimu- 

 lus or irritation of the hyphae than to any food supplied to them. 

 In this early stage it cannot be doubted that the algae are often 

 removed some distance from the parent cells and become the 

 centres of new clusters, which in fact could be found in all stages 

 of growth, showing from one to many gonidia. These clusters by 

 their increase finally anastomose, forming a more or less entire 

 surface from which the characteristic thallus develops. That this 

 was not the usual method of extension will be seen below, and it 

 was also manifest from the numerous germinating spores that 

 often appeared in the clusters, and also from the tendency of the 

 free mycelium to turn back toward its cluster soon after its exit. 

 While the spore (Fig. 6) was the prevalent one, there also appeared 

 two other forms, some of which had germinated. Owing, how- 

 ever, to the entanglement of the filaments it was impossible to see 

 how extensive was the growth of the odd spores. And the ques- 

 tion arises whether the hyphae of various spores may enter into 

 the structure of a lichen, and the dominant one characterize the 

 resulting thallus. In looking at these clusters of filaments and 

 algae the thought often occurred that could Crombie have seen 

 them he would not have made so spirited and bitter an attack 

 upon the theory of Schwendener, nor would the latter have ap- 

 peared so highly colored or poetical to him.* 



After the young symbionts became accustomed to their new 

 surroundings in the laboratory there soon was manifest the 



