C. A. BARBER. 39 
has commenced, swell up considerably and become shorter and 
even globular (figs. 2 and 5). 
The occurrence of sieve-tubes in the haustoria of green hemi- 
parasites has not been, it is believed, observed before. Peirce,’ 
who investigated a number of cases, found that in Lathrea, 
Brugmannsia and Cuscuta, colourless parasites, sieve-tubes were 
abundant, while they were absent in Viscum, a green hemi- 
parasite, a result which is in agreement: with what has been noted 
in Santalum and Olax and was also proved for Buckleya by 
Kusano. The presence of this complete vascular connection 
between host and parasite, usual only in cases of holo-parasitism, 
opens the way for interesting speculations and experiments 
regarding the nutrition of such plants. Auda more careful 
examination of all the other cases of self-attached hemi-parasites 
is called for. It is not likely that Olax will be singular in this 
respect. 
Borany ScHoou, CAMBRIDGE, 
June 1907. 
'G. J. Peirce, id. 
