X * 



EXPLANATION OF PLATE I. 



ILLUSTRATIONS IN GROSS ANATOMY. 



Fig. i. Diagram of an open flower of Trillium showing the 

 number and relative position of the parts : s sepals, p petals, st 

 stamens in two whorls, c carpels each bearing two ovules. Drawn 

 with pen. 



Fig. 2. Diagrammatic drawing of Marchantia to show the mode 

 of branching, somewhat enlarged. As one branch of each new 

 dichotomy soon distances the other, it produces the appearance of a 

 main axis with right and left branches : an the extension into 

 an antheridial branch, ar extension into an archegonial branch, y 

 recent dichotomy, o o' older dichotomy in which o' is already per- 

 ceptibly longer, c cupules which arise at the growing end of the 

 midrib and are left upon its upper surface as the stem advances. 

 Drawn with pencil. 



Fig. 3. Flower of radish, greatly enlarged and modified by the 

 growth of Cystopus within it, natural size. The change induced 

 by Cystopus is variable, sometimes single flowers are enlarged, as 

 in this case, sometimes the whole cluster of flowers is changed 

 when the individual flowers remain smaller. This example is 

 larger than the average size. Drawn with pencil. 



Fig. 4. A small fruiting plant of Atrichum, X 2 : the stem bears 

 scale leaves below and foliage leaves above, the base is clothed 

 with rhizoids that simulate roots, st seta, sp capsule sur- 

 mounted by the closely fitting calyptra. The distance the beak 

 extends into the calyptra is indicated. Outline drawing with pen. 



Fig. 5. Flowering head from a vigorous male plant of Atrichum, 

 X 2 : the difference between the perichaetial and foliage leaves is 

 well shown. Drawn with pen. 



Fig. 6. Pod (seed vessel) of Capsella, X 2. Drawn with pen. 



