340 CuHuRCH: THE BULB IN COOPERIA DRUMMONDII 
solution of the fixing agent was found preferable to an alcoholic 
solution, since in fixing material such as Amaryllis the alcohol 
evidently causes a coagulation of substances present in the scales 
and possibly in the bulb axis. To hasten the penetration of the 
material by the fixing agent, the object as soon as dropped into 
the acid was placed in a chamber from which the air was exhausted 
until the large size of the bubbles arising from the cut surface 
of the tissue indicated a fair approach to a vacuum. The air 
was allowed to replace the partial vacuum very slowly without 
outside aid. The use of the exhaust chamber was also resorted 
to with every change of alcohol, alcohol and ether, and ether. 
The fixation was practically perfect owing to more immediate 
and entire penetration. It did not, however, secure even moder- 
ately good fixation of incipient roots which were wholly within 
the bulb axis. Prior to killing and fixation, the bulb was trimmed 
down to about six scales, if the purpose was merely the examination 
of the youngest portions. Thorough fixation was thus more easily 
secured and the vegetative point was not crushed by the heavier 
parts. 
Washing was carried on in water for two days and completed 
in the low grades of alcohol, such as 20-70 per cent. The general 
celloidin method was followed from here on until the actual 
point for embedding was reached. At this point in the work, the 
object, after the removal of the superfluous celloidin, was hardened 
in 70 per cent alcohol and then in chloroform for two hours. It 
was transferred from the chloroform to 85 per cent alcohol. 
The usual paraffin method of imbedding was now followed (5)- 
Material prepared in this way sectioned with unusual smoothness 
and ease. 
The rotary microtome was used in all paraffin work except 
where bulbs or pieces of material were too large for the section 
block. Such large pieces of material were mounted on blocks of 
wood, trimmed out underneath until small enough to be placed in 
the jaws of the sliding microtome clamp. In handling individual 
paraffin sections as large as, or larger than, two inches square, a 
vessel of warm water was kept at hand. The sections placed 
carefully on the surface of the warm water uncurled readily, with 
no danger of cracking. It is necessary to see that the water is not 
