ANOTHER KIND OF GROWTH. 59 



separated, and the bud or offset becomes a free and in- 

 dependent particle, exactly resembling that from which 

 it sprung (except that it is smaller), and capable of 

 growing and giving rise to new individuals like itself, 

 by a repetition of the process by which it was formed. 



93. Aiiotlier kind of growth. — The above is one 

 way in which the particles may multiply, but there 

 are others. In one of these, too, an orifice forms in 

 the membrane of the particle of mildew, and a Httle 

 of the soft transparent material escapes, but it does 

 not separate as in the first instance ; it remains 

 in connexion with the mass, and grows out into a 

 narrow thread-like process. A long undulating stem 

 gradually results, from various parts of which new 

 buds proceed which grow, and branch like the original 

 one, and sometimes with astonishing rapidity. At 

 first the membrane or formed material of these 

 branches is extremely thin, but it gi-adually becomes 

 thickened by the deposition of new formed material 

 within, until it acquires considerable firmness, and 

 at the same time it increases in breadth. If the 

 conditions cease to be favourable to growth, the 

 branches cease to extend, and the membranous 

 protective covering acquii'es increased thickness. 

 Within the sheath is found the transparent matter, 

 from which a number of little spherical bodies or very 

 minute gi'owing particles like those observed within 

 the spherical spore may be obtained. 



94. Increase of bioplasm and prodviction of formed 

 material. — These two processes — the extension of 

 bioplasm and the production of formed material — 

 occur under different and often opposite conditions ; 

 the circumstances favom-able to the rapid increase of 

 bioplasm being unfavourable to the production of 

 formed material, and vice versa, so that an abundant 

 supply of pabulum is associated with rapid growth of 

 the bioplasm, a scanty supply with the production of 

 formed material. The former is a very rapid process, 



