668 
Benson.—Root Parasitism in Exocarpus. 
The haustoria that had been preserved in spirit were therefore cut, and 
the series of microtome sections carefully stained by my friends, Miss 
Chambers and Miss Welsford, to whom my thanks are due for making the 
best of rather hurriedly preserved material. The slides exhibited features 
in the conducting tissue of the haustorium which had not previously been 
recorded for Santalaceous haustoria. Last 
summer, therefore (August, 1909), I collected 
a large number of the haustoria of Thesium 
in Canton Valais, Switzerland, for compari¬ 
son. These were also cut with the micro¬ 
tome and stained in the same way. 
The latter preparations have been of 
great use to me as they have shown clearly 
that the haustoria of Exocarpus , while agree¬ 
ing in many particulars, differ in others from 
those of hitherto described Santalaceae. If 
I enter into some detail in describing these 
haustoria it is because no previous descrip¬ 
tion based on microtome serial sections of 
such structures seems to have been pub¬ 
lished. 
Heinricher’s detailed papers 1 deal with 
no member of the Santalaceae. Pierce 2 
treats of Cuscuta and other genera whose 
haustoria are by common consent of different 
origin from those of the Santalaceae. Solms- 
Laubach’s 3 valuable monograph was pub¬ 
lished so long ago as 1867. 
ToDr - Barber ’ s 4 work on other mem - 
roots by means of variously shaped bers of Santalaceae frequent reference will 
The foreign roots, X, are shaded. ^e made. Ilis interesting papers should be 
The branching of the Exocarpis root consulted by any one who wishes to realize 
is apparently abnormal on either side . ..... 
of the pointer, E. the range ot problems involved in the investi¬ 
gation of the parasitic habit of the Santa¬ 
laceae. It is much to be regretted that they have been published in 
memoirs not ordinarily accessible to students. It is only from his own 
statement that we learn he was hampered in the use of the microtome by 
the unfavourable climate conditions of Madras. 
1 Heinricher : Cohn’s Beitrage z. Biol. d. Pflanzen, B. 7, ii, 1895; Pringsheim’s Jahrbuch, 
vol. xxxii, 189S; Ibid., vol. xxxvi, 1901. 
2 Pierce: Annals of Botany, vii, 1893. 
3 Solms-Laubach : Ueber den Bau und die Entwicklung parasitischer Phanerogamen. Prings¬ 
heim’s Jahrbuch, vol. vi, 1867. 
4 Barber, 1 . c. 
