234 Vn'wcrsil !i of Colifoniia riihlicdf ions In fiohnni | N oi,. 7 



X. DlSTKir.l'TlOX OF UriiP.EH IX TIIK PLAXT 

 </. KFXaONAL DISTRIBUTION iX THK i'LAXT 



Since our iiuiiii ciuleavors have l)i'('ii dirceted to an examination 

 of ;i laf<:e nunil)ei' of individual plants of a iiiiiiihei' of species of 

 Chri/sothainnKs and otlici- <>'enera, no <ii'cat attention lias been <>;iven 

 to many interesting and perhaps ultimately important details which 

 have to do w itii anatomieal peculiarities and with tlie ori<iin and occur- 

 rence of rul)l)er, whieh. under other circumstances, mijjht well have 

 concei'ned us. Intleed. various causes have resniti'd in an accumula- 

 tion of studies much less detailed concernino- these matter.s than was 

 ori<»inalIy anticipated. Again, since our interest lay pi-imarily in 

 discovering the average rubber content of the main rubber bearing 

 tissues and since it was early seen that the latter were peculiar to the 

 older parts of the stem, the younger portions of both stem and root, 

 the study of which is necessary for a thorough elucidation of the 

 problems of the origin and occurrence of rubber, were not usuall}' 

 collected in the Held and wei'e thus not available for stiuly in many 

 cases. At the present time, however, we are prepared to make certain 

 general statements concerning the distribution of rubber in ttie plants 

 with which we have been concerned, and leave for further description 

 a number of matters which are still under investigation. Particularly, 

 we aim in what follows to interpret for such persons as may concern 

 themselves with histological examinations of plants suspected of con- 

 taining rubber, the appearance of the sections wdiich they will be 

 likely to obtain and to indicate to them the nature and distribution 

 of the tissues in which rubber may be expected to occur. In this 

 endeavor we will emphasize the results of our histological studies, but 

 will also draw upon those derived from chemical analysis. 



Attention has already been called to the fact that as in (hiayule, 

 so in Chrjjsothamnus we are dealing with a non-latex rubber which is 

 found deposited as such within the individual cells of certain portions 

 of the plant body. It may be noted in passing that many persons, 

 <'ven at the present time, are not acquainted with the nature of the 

 oeeui'rence of r(d)ber in (;ua\ule, noi' with the consetjuent processes 

 of extraction, tlie latter differing so decidedly fi'om those employed 

 ill the case of plants which bear latex-rubber. Since identical or simi- 

 lar i>rocesses will undoubtedly be employed should ("hi-ysil at any 

 time prove of sufficient importance to warrant its extraction on a 



