276 PHYLUM XII. CYCADOPHYTA 



Laboratory Studies, (a) In many greenhouses may be 

 found well-grown sj^ccimens of Cycas and Zamia. Examine 

 these for the general appearance of Cycads. 



(b) On inquiry it is possible that microspore cones of these 

 common Cycads may be found, and secured for a closer study. 



(c) Old trees of Cycas produce their '^ flowers" of mega- 

 sporophylls every few years, and on inquiry some of the latter 

 may be secured in various stages of development for dissection 

 and study. 



(d) Zamia plants in greenhouses frequently produce their 

 thick, rounded megasporophyll cones. These should be dis- 

 sected to find the sporangia (seeds). 



(e) It should be remembered that various Cycads, including 

 Cycas and Zamia, grow in the Gulf states, and specimens may be 

 obtained for study without much difficulty. 



(/) Ginkgo trees are grown in many parks and door yards, 

 and may be examined for their foliage and general appearance. 



(g) In the spring look for microsporophylls and megasporo- 

 phylls of Ginkgo and later for ripe, fleshy seeds. 



(h) From the middle of June to early in July, depending 

 upon the location, the sperms can sometimes be observed in the 

 seeds as follows: Take a seed and with a stout knife split off 

 two opposite sides (including the stony part of the integument). 

 If properly made a slice will be removed from each side of the 

 megagametophyte which can be removed with a portion of 

 the megasporangium (nucellus) adhering as a cap to its apex. 

 Upon carefully lifting this cap the microgametophytes will be 

 found hanging to its under side as thick, glistening, tube-like 

 bodies. Carefully dissect these off with very sharp scalpel 

 and mount in a solution containing about 5 per cent, of cane 

 sugar. The sperms (or at least the cells from which they arise) 

 will readily be visible even under low power of the microscope, 

 as they are very large, attaining a diameter of 0.1 millimeter. 



LITERATURE OF CYCADOPHYTA 



J. M. Coulter and C. J. Chamberlain, Morphology of 



Gymnosperms, Chicago, 1910. 

 M. C. Stopes, Ancient Plants, London, 1910. 



