64 ELEMENTAEY BIOLOGY. [VII. 



with regular transverse thickenings on their 

 walls and spiral vessels, less numerous than the 

 last form : with a continuous spiral thickening 

 on their walls. 



7. The bast-cells : seven or eight times as long as 

 they are broad, and terminating obliquely at 

 each end. 



B. The elongated larger cells (4. d. B.) : they have 

 very slightly thickened walls and no scalariform 

 markings. 



6. [Cut off half an inch of the growing end of the stem, imbed 

 it in paraffin upside down, and cut a series of transverse 

 sections : examine them with the microscope, beginning with 

 those farthest from the growing point. At first the various 

 tissues described in 3 and 4 will be readily recognisable ; as 

 the sections nearer the growing point are examined they 

 will be less distinct, and close to the growing point the 

 whole section will be found to be composed entirely of 

 parenchymatous closely fi.tting cells.] 



[c. The lea<f. Imbed a leaf in paraffin and cut a thin 

 vertical section : examine with 1 inch obj. It will be 

 found to be constructed essentially on the same plan as 

 the leaf of the bean. (VIII.)] 



d. The reproductive organs. 



1. Examine a soriis with 1 inch obj. without a cover-glass. 

 It is composed of a great number of minute oval bodies, 

 the sporangia. 



2. Scrape off some sporangia and mount in water: ex- 

 amine with 1 inch obj. 



a. Their form: they are oval biconvex bodies borne 

 on a short stalk. 



