INTRODUCTION 3 



the presence of such a mucus by selccti\e stains. Mr. H. R. Tottcn, 

 Instructor in this lalioratory, has carried out a scries of experiments on the 

 emerging sjiores of Achlya and has used various stains in an attempt to 

 determine the presence of a mucus. lie reports as follows: "I have been 

 unable to demonstrate the presence of a mucus in the six)rangium while 

 the spores are moving towards the central axis, or about the escaping 

 spores, or about the spherical mass of spores at the tip of the sporangium 

 after their escape. The following stains have been used: Delafield's 

 Haematoxylin, Methylene Blue following Lead Acetate and without Lead 

 Acetate, Chloroiodide of Zinc, India Ink after growing plants in i% 

 Congo red." On account of the even distribution of pressure through- 

 out the sporangium, which would follow if the expellent material were 

 simply a watery sap, the grouping of the spores into an axillary row 

 while emerging, and their e^•ident attraction to each other would have 

 to be explained on the assumption that they actively cling and press 

 together. Heretofore no explanation has been offered for these striking 

 facts except the \ery unsatisfactory suggestion of a kind of liking for 

 each other, the adelphotaxy of Hartog. Humphrey (p. 76) fa\-ors this 

 explanation and also asserts the opinion that there is no material con- 

 nection between the spores. Realizing the unsatisfactory state of this 

 whole matter, we ha\'e been carrying on recently with the help of se\'eral 

 of our students an examination into the spore discharge in Achlya, 

 Aphauomyces and Leptolegnia. and we are now prepared to add some new 

 data on this puzzling subject. 



Rothert ('88) has shown that the spores of Achlya polyandm are 

 connected by threads on emerging, and later ('03) found that the same 

 istTueiov Aphanomyces. iNIr. J. N. Couch, Instructor in this laboratory, has 

 confirmed these obser\-ations and has pro\ed that there is a material 

 connection between the spores in Achlya, Aphanomyces and Leptolegnia 

 while in the sporangium, and that in the first two this connection is main- 

 tained until the spores have taken their position in the apical ball. It 

 is our opinion that these connecting strands play the most important 

 part in drawing the spores into a ball in Achlya and Aphanomyces and 

 in holding them there. This remarkable phenomenon has heretofore 

 received no adequate explanation. Rothert thinks the spores are held 

 together in a ball by a gum but as said above we find no such substance. 

 In his first treatment of the genus Aphanomyces, deBary demonstrated 

 the presence of a slender filament of protoplasm connecting the emerging 

 spores in the sporangium ('60, pi. 19, fig. 3), but he said that at times 

 they were without this connection. In our experience, when this con- 

 nection is absent it is evidence that the sporangium will not empty and 

 that the spores ha\"e reorganized themsehes for a rest. 



