Living specimens were obtained from an extremely flourishing culture maintained by adopting Leeson's method (1932), and the insects were anaesthetized and dissected in physiologically normal saline for observing living movements of the proventricular walls. Proventriculi were also teased out in normal saline for studying the spines. Mounting of freshly teased out spines in the DeFaure's fluid tinted light pink with borax carmine yielded excellent results. Different fixatives were tried but Carnoy II was found to be most satisfactory. Double embedding (celloidin and paraffin wax) method was employed for cutting serial sections. Delafield's haematoxylin and eosin were mostly used for staining. The "blow and roll" technique devised by the author and described below, proved to be of a great help for the study of the entire surface anatomy of the organ, including the arrangement, pattern and distribution of the spine bases, and for calculating the total number of proventricular spines in both the sexes. Freshly dissected out proventriculi were allowed to float freely in normal saline contained