1918] BUCHHOLZ—PINUS Igl 
forceps with which the gametophytes are held should be small and 
have weak springs, in order to avoid crushing the tender tissue. 
With the dissecting tool B the end of the gametophyte is removed 
along the line xy. By teasing a little deeper into the tissue around 
the edges of the archegonia it is possible to loosen the embryos 
at the bases of the archegonia, allowing the rosettes to be pushed 
out by the suspensor as in D, text fig. 1. 
Usually a little gentle stroking with slight pressure in the 
direction a to 6 with the dissecting instrument held nearly hori- 
zontal (to avoid crushing the tissue) is sufficient to loosen the 
embryo and gradually force it out. A slight pressure with the 
forceps on the sides of the gametophyte at the proper moment 
may help. Sometimes gametophytes must be split vertically 
along the line ab before the older embryos can be removed. 
When the embryos are imbedded more firmly, it may be impos- 
sible to dislodge them by these methods. Sometimes it has been 
found possible to remove embryos with the complete suspensor 
system by chipping away pieces of the gametophyte, first from 
one side and then from the other. This is accomplished most 
easily by rolling the gametophyte over after each chip has been 
removed, cutting off pieces x; x, x; (text fig. 1, C) alternately, until 
the embryos are sufficiently loosened. Any method of pulling the 
embryos out by taking hold of the upper part of the suspensors 
without first loosening the embryos below results in an incomplete 
embryo and suspensor system. In spite of the greatest care and 
perseverance it is often impossible to remove the suspensors and 
embryos without some of the latter breaking off. Which of the 
preceding methods is to be used will depend somewhat upon the 
condition and stage of development of the embryos. 
In the earlier studies, which were carried out in this manner, 
many embryos were found abnormal, in which the protoplasts 
had escaped from the cells and could be found as dark staining 
masses near the empty cells. Careful study revealed the fact that 
this was an osmotic phenomenon, due to the fact that the dissection 
was executed under water. The cells have a high osmotic pres- 
sure, and when placed in water they swell and break in a short 
time. This may be avoided by dissecting the embryos out under 
