SPERMATOPHYTES— GYMNOSPERMS 



323 



The vegetative structures. — All the vegetative structures cut rather 

 easily. 



The stem. — Zamia, which grows in various parts of Florida, is the 

 most available material. Directions for handling the stem are given 

 on page 140. 



Stems of the larger cycads are not likely to be obtained, except in 

 the field, and they are confined to tropical and subtropical regions. 



Fig. 110. — Dioon spinulosum: photomicrograph of transverse section of wood, cut from fresh 

 material. X1^5. 



Cycad stems cut better while fresh (Fig. 110) but, fixed in formalin 

 (10 c.c), acetic acid (5 c.c), and water (85 c.c), fleshy stems like 

 Zamia and Ceratozamia cut well, even after years in the solution. 



A piece of cycad trunk 15-30 cm. in diameter and 20 cm. in length 

 will survive a journey of 6 weeks or even 2 months, if care be taken to 

 coat the exposed ends with a mixture of melted paraffin and moth 

 balls, using 3 or 4 moth balls as large as marbles to half a kilo of 

 paraffin. If material is to be fixed before cutting, use 6-10 per cent 

 formalin in water. 



Dr. La Dema Mary Langdon succeeded in cutting paraffin sections 

 of the adult wood of Dioon spinulosimi. She fixed 1-2 cm. cubes of 

 adult wood in formalin-acetic acid-alcohol (6 c.c. formalin, 3 c.c. 



