396 



Mr. C. H. Martin. 



[May 10, 



Prof. Minchin for allowing me to write up these notes in his laboratory at the 

 Lister Institute. 



Of the forms which I cultivated from the sick tomato-soil a rough list 

 will be found at the end of the paper. In this note I wish to describe a 

 flagellate which passes through its life-cycle in my cultures, terminating in 

 the formation of a zygote-cyst,* with great regularity. I do not propose to 

 enter into the question of the nomenclature of this form in any detail here. 

 It appears to me to be identical with the flagellate figured by Stein as 

 Cercomonas tcrmo, which he identifies with Monas termo of Ehrenberg, and 

 which is therefore presumably identical with the Oikomonas termo of 

 Biitschli. The trophic form of this organism is a roughly spherical animal, 

 provided at its physiologically anterior end with a single, rather short, thick 

 flagellum (Plate 10, fig. 1). 



The size of the animal may be somewhat variable. In young cultures, in 

 which no gametes occur, the active forms seem to measure about 4-5 /j, t 

 whereas in the older cultures larger forms are met with. The body, 

 particularly at its posterior end, contains large rounded vacuoles. These 

 vacuoles may disappear, and are probably mostly food-vacuoles, and I 

 cannot find any evidence for the existence of a true contractile vacuole. 

 In life, the posterior end of the body may undergo amoeboid movement, and, 

 more particularly in actively swimming forms, the body may assume a 

 rather more elongated shape than in the resting form (fig. 2). The body is 

 often found crowded with ingested bacteria, and a number of small granules 

 which appear to stain reddish in neutral red. In life, a nucleus, with a 

 fairly large caryosome, can be distinguished clearly. In stained forms the 

 flagellum can be seen to arise from quite a large blepharoplast, which stains 

 vividly in iron-hsematoxylin. The nucleus in the stained preparations is 

 large and vesicular. Most of the chromatin appears to be contained in the 

 caryosome, but a certain amount seems to be present on the nuclear wall 

 (%• 1)- 



The division in this monad seems to be initiated by the division of the 

 blepharoplast (fig. 3), but this is quickly followed, or possibly in some cases 

 preceded, by the splitting of the flagella. Up to the present I have found 

 no evidence for the outgtowth of new flagella in the dividing forms of this 

 animal. The nucleus up to this stage presents its characteristic appearance 

 of a dark caryosome lying in a large nuclear space. It quickly becomes 

 much darker, and the whole space is crowded with relatively large 



* It is unfortunately impossible at present to prove conclusively that this process is 

 not an autogamy, since up to the present I have not carried cn continuous observations 

 on conjugating forms in life. 



