November, 1910. 



K\0\VL]£DGE. 



437 



into the interior of the monad and is rapidly 

 disintegrated. During this process the long flagelkim 

 is usually vibrated with intense rapiditw Not 

 only bacteria, water plants, and other monads 

 are ingested in this manner, but also smaller monads 

 of the same species, the feeding monad becoming 

 ver}- large in consequence. In one large specimen 

 that I had under observation continuouslv for nine 

 hours, five smaller monads of the same species were 

 ingested. Three more were captured, but bv intense 

 flagellar movements they \\ renched themselves free 

 and escaped. There is no doubt that a kind of 

 gastric juice of an acid nature is secreted hv this 

 monad, as I have found that if bacteria are stained 

 with a saturated solution of blue litmus, and intro- 

 duced into the water in w hich this monad is living, 

 on ingesticm they are almost instantl}- turned red. 

 After feeding in this wa\' for some time, the monad 

 again becomes amoeboid and finalh" takes on the 

 normal sausage-shaped form, and active s\\ imming is 

 recommenced. This period of alternation between 

 swimming and taking on a globular form, with a repeti- 

 tion of feeding operations. ma\- continue tor man\- 

 hours. Finally, however, the organism comes to a stand- 

 stillandbecomes e.\tremel\amoeboid,the bod\" getting 

 very granular. Sluggish swimming now occurs, the 

 body being in intense amoeboid action. Wliile the 

 organism is in this condition, another normal form 

 comes into contact with it, and almost instant fusion 

 occurs, the long flagellum being vibrated with 

 remarkable rapidity. The organism now speedih- 

 becomes globular, the long flagellum being cast 

 off, and the smaller one fusing with the 1kk1\-, 

 a motionless globular sac is formed, which gradualh- 

 becomes very granular, the granules showing move- 

 ment. This sac ma\' remain in an absoluteh" 

 motionless condition for a period which \aries from 

 six to ten or more hours. Finalh', however, it 

 bursts at one end and liberates a number of small 

 granules about a thirty thousandth part of an inch 

 in diameter ; these roll away from the sac, and if care- 

 fully followed soon show signs of growth. In about 

 two hours they acquire flagella. in what manner I 

 have not yet been able to determine, though I think 

 the long one is suddenly shot through the bod}- \\all. 

 This method of reproduction was alwavs obscure 

 and was only discovered after months of work on the 

 form. In the two conjugating individuals there was 

 this essential difference, viz : that one w as the 

 ordinary sausage-shaped free swimming form, which 

 was much smaller than the other amoeboid form : 

 this latter by long feeding had greath' increased its 

 size to several times that of the other and was far 

 more granular. The other method of reproduction 

 was by fission, and this occurred in the ordinary 

 form after it had attained a certain average size in the 

 following manner. After nuclear division, a con- 

 striction was developed round the body of the 

 monad which divided it into two : one of the 

 two nuclei now passed into each half and the 

 constriction deepened : the smaller flagellum now 

 gradually appeared in the end most remote from the 



other two flagella. From this time the constriction 

 rapidly increased and the flagella lashed in a manner 

 which pulled the two halves away from each other. 

 Finally, they moved away from each other, the thin 

 connecting strand of protoplasm breaking close to the 

 body of the monad possessing the two normal 

 flagella, and this protoplasmic strand formed the long 

 flagellum of the other form. Periodicallv, the 

 organism ejects undigested matter, this usually being 

 at the opposite end to the flagella. A rather 

 characteristic appearance is thus often given to the 

 organism, as the effete matter gradually accumulates 

 round the body and remains there for some tiine, till 

 finall}- being cast off. The important points with 

 regard to this organism are I think the following: — 

 Firstly, that although presumably a certain amount 

 oi saprophytic nutrition does take place during 

 active swimming, the organism is unable to obtain 

 the requisite amount of nutriment bv sapro- 

 phitic means alone, but is compelled to ingest 

 other organisms of as complicated a chemical con- 

 stitution as itself, this method of nutrition being 

 eminently holozoic. Secondly, the fact that, although 

 there is no buccal opening, yet food is ingested at 

 one particular spot, viz : between the roots of the 

 two flagella, coupled with its method of nutrition, 

 gives to this monad a higher position in the scale of 

 organisation than any other known members of the 

 family: and, third!}-, so far as I. am aware, there is no 

 other known instance among the Protozoa of what 

 one ma}- well call a cannibal form. 



The anisogamic method of reproduction in thisform 

 is of considerable interest, inasmuch as the two 

 conjugating forms differ in several respects. The 

 larger organism or megazooid having increased its 

 size greatly b}- continued ingestion of other organisms, 

 and, apparentl}- in consequence of its increased size, 

 is far more sluggish in mo\ement, besides being 

 e.xtremely granular and amoeboid. The microzooid 

 is the ordinary normal form, and is not amoeboid, 

 and, in size, is generally from one-half to one-third 

 the size of the megazooid ; it is far more active in 

 swin-iming, and, on several occasions, I have noticed 

 that the nucleus, which is ver}- difficult to observe in 

 most of the normal forms, was more prominent than 

 usual. Thus it will be seen that we have here a 

 method of reproduction resembling a true sexual 

 process, as both of the two conjugating gametes 

 differ from one another, not onl}- in size, but also by 

 the fact that the megazooid had, by continued 

 feeding on similar forms, laid up a store of 

 potential energ}- for further reproductive processes ; 

 whilst the microzooid had arrived at a certain 

 average size after reproduction b}- fission, and had 

 not commenced to feed on its own kind in the 



manner that the megazooid had done, its 



size 



apparentl}- precluding its ingesting other organisms, 

 as large as itself, although bacteria were easily 

 ingested. The ordinary method of reproduc- 

 tion by transverse fission, showed little that was 

 peculiar to this particular monad. On following 

 one of the discharged granules from the parent sac 



