LIFE-HISTORY OF PENICILLIUM. 855 
Two forms of branches, of similar origin but of different 
kinds, are thus produced from certain cells of the carpogonium 
after cultivation of from seven to eight weeks. It is an un- 
doubted fact that the thinner ones consume the sterile tissue 
of the sclerotium(Plate XVII, fig.5g). The walls of the cells 
in the neighbourhood become thinner and disappear, and 
these branches must be considered to be special organs of 
nutrition. ‘They are closed at the ends, and dissolve the 
tissue of the sclerotium and take up the nutrient substance 
in some unknown manner. ‘The fertilized carpogonium 
thus lives as a parasite in the eentre of the sterile tissue, 
but at no point has it any organic connection with the 
sclerotium. 
The thinner nutritive carpogonium-hyphe elongate by 
apical growth and increase by branching (Plate XVII, fig. 
9 d),so as to form a filamentous investment round the 
thicker tubes. As they grow the scope of their activity 
becomes greater, and increasing nutrition keeps pace 
with the growth. As long as the nutritive hyphe are 
active they possess few or no septa. Their course is 
irregular ; in many places they form dilatations, the cavity 
being double the ordinary width. Numerous twists and 
tendril-like turnings alternate with straight portions, and 
constricted parts are followed by dilated portions, and, again, 
these are suddenly followed by contractions. The diameter 
is from 0:0015 to 0:0025 mm., the wide portion being about 
0:0050 mm. 
The thick branches—those destined to form the fructifica- 
tion—have a very slow growth, but produce very numerous 
branches. ‘The first lateral branch is formed close to the 
apex and elongates, others forming which are packed 
closely together in a coil. From the frequent branching 
and the slight growth in length, the whole looks like the 
mode of branching in yeast; it, however, follows a regular 
plan. Only the ends of the hyphe can be observed, but 
there can be little doubt that the development of the other 
parts follows the same course. The short apex bends to one 
side in a somewhat snail-like manner, and on the convex back 
of the bent hypha the youngest branch is always developed. 
The main axis next turns about two thirds of a revolution 
to the opposite side, and another lateral branch is developed. 
This process, frequently repeated, must ultimately cause the 
formation of a serpentine main axis, on which the lateral 
axes are placed at very short intervals. As regularly as 
lateral branches are formed, so regularly are transverse septa 
deyelopedin the main axis, the youngest being always above 
