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prothallia is 60° F., although they will continue to do well in a 

 room whose temperature is much higher provided the culture 

 solution is not allowed to become overheated by exposure to the 

 sun's direct rays. 



Cultures may be labelled in various ways, but the most con- 

 venient one is to write on the cover of the capsule near the edge 

 with a glass pencil the name of the species, the solution used for 

 the culture medium and the date of sowing the spores. By ab- 

 breviating the name of the species and by the use of either a letter 

 or Roman numeral for the culture solution and of figures to indi- 

 cate the date, the inscription need not occupy much space. For 

 example, "A. S. — P. — 1% '20" = Aspidiuin spinulosum, Prantl's 

 Solution, November 4, 1920. Although it is not absolutely nec- 

 essary to label the cultures if only one species and one culture 

 solution are used, still it is well to have the date when the spores 

 were sown indicated. 



When the prothallia are distributed for laboratory study, it is 

 best to remove a part of the culture to a watch glass, being careful 

 to use clean instruments and to return the cover to the capsule 

 as s'oon as possible. Under a dissecting microscope by means of 

 needles, the prothallia may then be teased apart, as the rhizoids 

 frequently become interwoven, and placed in another watch glass 

 from which to be distributed to the students. In this way the 

 students secure better mounts, a great deal of time will be saved 

 and a waste of material avoided. If more prothallia have been 

 removed from the culture than are needed immediately, the re- 

 mainder can be kept in excellent condition by adding a few drops 

 of water and placing the watch glass in a moist chamber. This 

 moist chamber can be made by inverting a bell jar over a plate 

 in which a little water is allowed to stand. The prothallia may 

 be returned to the culture if care is used not to submerge them as 

 has been previously stated. 



Young sporophytes may be removed from the culture and 

 placed in watch glasses containing nutrient solution, supported by 

 tiny pebbles in such a manner that the young leaves are above the 

 solution and the young root immersed (Fig. 2). The watch 

 glass should be covered with a bell jar. These sporophytes 



