POLLEX-BODIES OF THE ANGIOSPERMS. 
21 
moist chamber. At first I tried solutions of cane-sugar of 
different degrees of concentration, but, as in many cases, no 
satisfactory results could be obtained in this manner, I tried 
other liquids. Van Tieghem,^ who also cultivated Pollen- 
bodies, recommends the addition to the liquid of une petite 
quantite” of acid tartrate of ammonia. T first of all decided 
that this petite quantile’^ could not be above 1 per cent., as 
stronger solutions would be simply deadly. Solutions of 
*1, *25, *5, and 1* were, on the other band, of no special use. 
The directions again of Van Tiegbem that inorganic salts, 
sugar, gum, and etheric oils should be added, according to 
the needs of the plants, are too general and uncertain to be 
worth wasting time over in further trials. After I had made 
trial also of a solution of glycerine one per cent, strong, and 
after trying solutions of nitrate of potassium and of carbonate 
of soda, I turned back to my solutions of cane-sugar (called 
in the following for the sake of brevity sugar solutions), as the 
most suitable. I made use of such solutions of different de- 
grees of concentration (as 1, 8, 5, 10, 20, 30, and 40), for, as 
might have been anticipated, it was soon apparent that the 
maximum degree of concentration required is different for 
the Pollen-bodies of different kinds of flowers ; while som.e 
Pollen-bodies developed tubes in almost any solution, others 
required a certain definite degree of concentration ; the indi- 
vidual variations in this respect were very remarkable. I 
is of great importance to use, for the purpose of cultivation 
quite ripe, though not over ripe. Pollen-bodies. 
Omitting minor variations I have given in the following 
pages the degree of concentration which proved itself the 
most useful in the culture of the Pollen of the several 
species of plants studied. I have also given the time in 
which the tube reached a certain length, under circumstances 
which were otherwise normal. Where no other solution is 
mentioned the cane-sugar solution was the one used. 
In all culture experiments the Pollen tubes swell after a 
time into club-like bodies, and finally finish off by bursting. 
In older tubes the still growing point is found separated 
by peculiar cellulose-plugs from the emptied posterior por- 
tions (see Strasburger, 1. c., p. 456). 
The culture experiments were undertaken with a tempera- 
ture as warm as the usual one of a room and in the dark. 
In many kinds of flowers the tube formation also took place, 
and in a normal manner, in the daylight. I did not turn my 
attention further to this point. 
At the same time I was, in the case of many plants, unable 
‘ Annales des Sc. Nat., 5 seric, t. xii, 1809, p. 318. 
