182 THE SAPROLEGNIACEAE 



Allomyces arbuscula Butler. Ann. Bot. 25: 1027, figs. 1-18. 191 1. 



Blastocladia strangidata Barrett. Bot. Gaz. 54: 353, pis. 18-20. 

 1912. 



Septocladia dichotoma Coker and Grant. 1. c. 



Plate 61 



Characters of the genus. Threads extending about 3 mm. from 

 the substratum on a termite ant, about io-37iJ, thick, growing grad- 

 ually more slender distally at each joint, basal joints 35-1301J. long, 

 those of central region up to about 675[a long; tips blunt, hyaline. Spor- 

 angia oval, 28-46 X 55-76^1.; spores escaping singly or at times, according 

 to Barrett, in a vesicle that soon bursts, emerging through one or two 

 usually apical holes or short papillae, biciliate (or uniciliate by fusion 

 of the two cilia?), oval when swimming, with the cilia apical, monoplanetic, 

 amoeboid before encysting, loij. thick when at rest; sprouting by a slender 

 thread. Resting bodies appearing later than the sporangia but of the 

 same shape, 25-39.2 x 36. 3-49. 2!i., the conspicuous pits apparently 

 sunken from the outside in regular fashion as in Blastocladia Pringsheimii, 

 at maturity slipping from the thin, clasping sheath; sprouting into zoo- 

 spores after a rest (Barrett). The thick wall is divided into two parts, 

 an outer layer (pitted) about i.8;a thick and a homogeneous inner one 

 about 1 [J. thick. 



Found only once, October 20, 1921, on a knuckle bone of beef partly 

 covered with water, in Sparrow's pasture, Chapel Hill, N. C. (F. A. 

 Grant, coll.). Reported heretofore only from India (Butler, 1. c), and 

 from Ithaca, N. Y. (Barrett, 1. c); but Dr. ^^'eston of Harvard writes 

 me that he has it from the Philippines. 



Butler places the genus in the Leptomitaceae, but it seems to us 

 that there can be no doubt of the close relationship of this plant to Blas- 

 tocladia, in which genus it was placed by Barrett. From accounts by 

 Butler and by Barrett there appears to be practically no difference between 

 their plants and ours. Butler gives the maximum length of the resting 

 spores as 6o(j„ but the difference is probably of little or no importance. 

 We had unfortunately overlooked these two papers in recording our plant. 

 Barrett gives interesting cytological detail. He found pores in the cross 

 walls of his form. Butler does not record these nor have we found them. 



In the form of the sporangia and resting cells and in the absence of 

 sterile filaments among them our plant resembles most closely B. ramosa 

 and B. prolifera. The remarkable resting bodies with their thick brown 

 strongly pitted walls and peculiar habit of slipping at maturity from 

 the closely fitting sheath are so strikingly similar in structure and habit 

 to those of B. rostrala and B. prolifera, and in structure to those of B. 

 Pringsheimii, that one is con\'inced of their close relationship. 



In a discharging sporangium a few spores that failed to get out were 

 observed to crawl about actively in an amoeboid fashion for a good while. 



