INTRODUCTION II 



of the vegetative threads of Saprolegiiia and Achlya has, on the other 

 hand, received considerable attention from Dangeard ('i6), Meyer ('04), 

 Randolph ('12) and Giiilliermond ('20, '20b). These authors find this 

 material excellent for the study of the minute bodies known as chon- 

 driosomes (chondriomes, chondriokonts, mitochondria). The last named 

 author has also studied carefully the origin of the vacuoles in Saprolegnia 

 and as he has given much attention to these subjects in a number of well 

 balanced studies it will be of interest to give some of his conclusions in a 

 recent summary of his results ('20), as follows (translated and adapted): 



"With the help of vital stains one may see that in very young fila- 

 ments the system of \acuoles is composed of long little canals that 

 anastomose in a network which by swelling and fusion finally form a 

 large vacuole, a sort of large canal occupying the whole axis of the fila- 

 ment. The little canals and the netvv^ork are filled with a substance in 

 solution that stains quite strongly. When the central canal is formed 

 this substance, being more diluted, stains in a much paler manner. The 

 systfem of vacuoles also contains, except in the initial stages, bodies that 

 stain in a more marked manner than the substance dissolved in the 

 vacuolary sap. Some show only after vital staining; they are strongly 

 stained and in a very metachromatic manner. The others appear in 

 the form of corpuscles, often quite large, with a refraction quite marked 

 and visible without staining. Osmic acid gives them a slightly gray 

 tint. The vital stains color them only feebly. After fixing in alcohol 

 or formalin and staining with methyl blue the system of vacuoles does 

 not show the characters shown in the living state. The vacuoles are 

 uncolored except for only little grains, some strongly colored with deep 

 violet and others tinted with pale blue. Haematoxylin does not color 

 the first and gives to the second a diffuse tint. These two groups of 

 corpuscles, which are perhaps only difi^erent states of the same substance, 

 do not show the characters of the granules drawn in the fungi under 

 the name of metachromatic bodies. 



"The employment of appropriate methods allows one to obtain 

 excellent differentiation of the chondriosome which appears in the same 

 manner that it showed when living. These methods do not stain the 

 contents of the system of vacuoles except in exceptional cases, when 

 the preparation has turned out badly. The fixations of commercial 

 formalin followed by staining with iron haematoxylin put in evidence 

 with the greatest clearness the nuclei and the chondriosomes. The 

 methods of Benda and of Kull differentiate also the fatty granules which 

 appear brown with osmic acid. With all these methods the chondriosome 

 appears to be made up of numerous particles (chondriokonts) of vari- 

 able length, which are differentiated very clearly by their intense colora- 



