iinitoDuc^^iOK. 



During the summer of 191'^ an elaborate invest J gition 

 was rmder taken by the Maryland State Weather Service in ooop- 

 eration with the T^ahoritory of Plant T>':---;j olo^-y of the ITohns 

 Hopkinr University, v/ith the object of ascertaining some of 

 the relations between olimatio conditions and the growth of 

 certain -'-.lants at different st^.-^ions i.n Maryland. T)etailed 

 information as to the growth of the plants used is of coxirse 

 necessary, as is 'also corresponding knowledge of those envi- 

 ronmental -'onrl i ti ons that are considered as cli>a'*"5o. The 

 plant records were secured in this case by gi'owing cultur;^s 

 of certain plants in the environmental conditions to be 

 studied an-i. noting the growth made during definite i^ei^iods 

 of time. In order that a corresponding series of .".easure-. 

 Eents of some of the environnental conditions might be avail- 

 able ■''or comcarison with therae growth measuremf^rtp +-'-•- n';:i+nres 

 were located 8,t certain of the regular U. S. 'Veather Bureau 

 obRervaticn stations at various places in the sti+e. '^he 

 general plan of the stuly and a detailed consideration c-"' 

 the methods used has already been printed by McLean^, -A-ho 



X' McLean, ?. T., A preliminary stiidy of clima'^ic conditions 

 ^n Maryland, as related to plant growth. :^hysiol. Res. 2: 

 129-808.1917. 



did all of the field work personally. "-.e original data 

 dealt with in the present naper are taken from the records 

 obtajne-"! by McLean ann it will be necessary to give here only 



