SECT. I 



MORPHOLOGY 



11 



The Development of Form in the Plant Kingdom 



The Thallus ( 10 ). When the body of a plant is not differentiated 

 into separate members, or is composed of members which (though they 



may be similar) are not 

 homologous with those of 

 the most highly organised 

 plants, it is termed a 

 THALLUS. When the Fl - 2 --- s '"" *? 



,, ,, . ,.. . , txrevisiae. 1, Cells 



thallus is differentiated wlthout bu ds ; -i and 

 into members analogous 3, budding ceils, (x 

 to those of the higher 540-) 

 plants some confusion may arise from the 

 At same names being used for parts which, 

 Commencement of division ; B, since their origin has been distinct, are not 



(to the left) shortly aftendi vision ; homoloo-QUS 

 C', a resting stage, (x MO.) . S- 



The simplest form that we can imagine 



for an organism is that of a sphere, and this is actually the form of 

 some of the lower plants. A green growth often seen on damp 



Fm.i.-Gtottifa 



Km. 4. Bacteria from deposits on teeth, c, 

 Leptothi-ii' hum i//'x; "', the same after treat- 

 ment with iodine; b, Micrococcus ; c, Spin- 

 chaete dentium after treatment with iodine ; 



il. *pii-!Uit,ii .tntitiiji-rtiim. (X 800.) 



FIG. 3. Pinnului-iu viridi*. A, 



view ; B, lateral view. ( x 540.) 



walls consists of an aggregation of the microscopically small spherical 

 bodies of Gloeocapsa poli/dermatica (Fig. 1), an Alga belonging to one of 



