A New Endophytic Alga. 45 



Bracebridge Wilson describes these malformations as resulting in the 

 formation of circular holes. I had only one instance of a malformation 

 with a central hole, but I think that in this case the destruction of tissue 

 was certainly due to the action of the endophytic cells, for these were 

 extremely abundant in the very thin tissue surrounding the hole. It is 

 easy to suppose that, when once the denser cortical portions of both 

 surfaces had disappeared, the looser medullary portion would soon be 

 destroyed. 



The endophyte may or may not occur among the filaments of the 

 depressed surface of the malformation, and when it is present the injury 

 to the tissue is not generally so far advanced as that of the raised surface. 



The presence of the endophyte among the cortical filaments of both 

 surfaces of the thick mature frond would seem to imply that the infection 

 occurs when the frond is quite young and very thin. This perhaps would 

 also explain the bulging of the frond in the diseased portions, for an 

 infected surface becoming raised and swollen might, as it were, carry 

 up with it the whole tissue of a thin and delicate thallus. This, however, 

 is merely hypothesis for the mode of entry of the endophyte into the 

 plant, and the first stages of its life-history within the tissue are entirely 

 unknown to me. I have been unable to find any trace of the endophyte 

 in any younger stage than those I have described, probably because I have 

 had no young material to examine. 



Briefly to sum up the results of this investigation, there exists among 

 the cortical filaments of the frond of SarcopJiycus potatorum an unicellular 

 Protococcaceous Alga, which, so far as I am able to judge from the life- 

 history known to me, belongs to the genus Chlorocystis, and I have named 

 it as follows : 



Chlorocystis Sarcophyci n. sfi., cellulis globosis oblongis vel irregularibus, 

 10-40^ diam., in statu vegetativo viridibus, in matrice omnino inclusis, 

 collo destitute, zoogonidia emittentibus. 



Hab. in SarcopJiyci frondibus ad oras Novae Hollandias prope Geelong. 

 coll. J. Bracebridge Wilson. 



It differs from the species hitherto described, in that, while these inflict 

 no injury on the tissue of the plant in which they live, C. Sarcophyci pro- 

 duces conspicuous malformations, and, in consequence of the disintegration 

 which it in some way induces, its spores are enabled to escape from the 

 tissue. A study of fresh material might determine whether the endophyte 

 derives any nutritious benefit from the disintegration of the cells of 

 which it is the cause; whether, in fact, this is a case not merely of 



'Raumparasitismus,' but of true parasitism. 



FRANCES G. WHITTING. 



G 



