33i 
Marshall Ward. — On a lily -disease. 
as follows. The protoplasm, confined in a segment, goes on 
forming the ferment, until, there being no substance for the 
ferment to employ its energies on, the quantity of the latter 
becomes so great that it can no longer be retained, and the 
cellulose-wall undergoes softening at some point and is pressed 
forwards as a protuberance, a young branch. I imagine, 
moreover, that the continuous forward growth of the apex of 
any hypha takes place in a similar way, that is to say, the 
ferment-substance at the apex keeps the cellulose of the hypha 
at that place in a soft, extensible condition, and the pressure 
from behind stretches it and drives the tip forwards. 
Next comes the second point, the direction in which the 
hypha or branch is constrained to grow. If we carefully 
examine cases such as those shown in Figs. 27 to 30, it seems 
to me impossible to doubt that the hyphae exert an attractive 
influence upon one another, just as do the zoospores of certain 
algae, or as the contents of archegonia have been shown to 
attract spermatozoids, and the filaments of Spirogyra react on 
one another when conjugating 1 . A little reflection will show 
that, in principle, the cases I have here brought*to light are by 
no means isolated ones. I may simply remind the reader that 
the oogonia of certain Phycomycetes not only attract the 
antheridial branches 2 , but, if De Bary’s supposition be correct, 
even determine their formation ; then, again, the neighbouring 
sporidia of the Ustilagineae have long been known to conjugate 
in pairs, the connecting tubes taking the shortest course 
between the two sporidia 3 . Such junctions as I am describing 
are much more common than is generally supposed, and in all 
the cases known to me it is difficult to avoid the impression 
that the two (or more) bodies concerned are attracting one 
another in some way. When one sees a hypha deflected from 
its previous course through nearly a right angle as in Fig. 28, 
and I have seen cases in another fungus where the deflection 
1 v. Pfeffer, Unters. d. Bot. Inst. z. Tubingen, I. H. 3. 
2 Beitr. zur Morph, u. Phys. d. Pilze, IV. 
3 See esp. Brefeld, Bot. Unters. ii. Hefenpilze, 1883; De Baiy, Biol, of Fungi; 
also Marshall Ward, Phil. Trans., B, 1887, PI. 12. 
