QUARTZ ROD TECHNIQUE 



209 



QUARTZ ROD TECHNIQUE 



of physiologic processes, or during de- 

 fined physiologic states. (The same 

 can be said of pathologic processes.) 

 The results of this kind of study are 

 quite different from summations of the 

 records of dimensions of tissues taken 

 at unknown phases of physiologic proc- 

 esses and studied and measured after 

 unknown amounts of distortion. For 

 an example which demonstrates this see 

 Knisely, M. H., Bloch, E. H., and 

 Warner, L., cited above. 



2. The rates and changes in rate of 

 visible processes, most of which are 

 quite unknown today. Histological 

 sections reveal steps in processes which 

 have long cycles, such as the endome- 

 trial changes during the menstrual 

 cycle. They frequently fail to record 

 as sequences changes which are parts of 

 short cycles, the reasons being (a) that 

 the stages of short-cycle phenomena 

 appear in a collection of sections simply 

 as a frequency distribution of the states 

 of the observed structures and (b) that 

 the dimensions are so altered during 

 death, fixation and sectioning that 

 functional differences are quite obliter- 

 ated, jumbled, and obscured. Further, 

 all too frequently the series of sections 

 present no real indicator valid for de- 

 termining the sequence of the steps in 

 short-cycle phenomena. When motion 

 pictures are taken through the micro- 

 scope the method permits accurate 

 recording and measuring of the rates 

 of very rapid processes. For example, 

 Knisely, M. H., Eliot, T. S., and Bloch, 

 E. H., 1945, cited above, measured the 

 rate of formation of precipitates in 

 blood flowing through crushed tissues, 

 finding that the precipitates formed in 

 from l/8th to l/4th of a second while 

 the blood flowed from 100 to 150 micra. 

 In the future this method should make 

 it possible to measure, in organized 

 tissues, the rates of many visible phys- 

 iologic, pathologic, pharmacologic and/ 

 or therapeutic processes or responses. 

 It should make it possible to measure 

 the rate of formation of any visible end 

 product of in vivo chemical reactions. 



Further, and most important, the 

 study of processes as they occur fre- 

 quently makes it possible to determine 

 steps in chains of causation. If one 

 assumes that an effect cannot precede 

 its cause in time, then it is possible to be 

 certain that some phenomena do not 

 cause, but rather may be caused by, 

 others. 



3. The method should make it pos- 

 sible to obtain small samples of tissues 

 and/or fluids from defined micro- 

 anatomical regions, during defined 

 phases of physiologic and/or pathologic 

 processes. Wearn, J. T. and Richards, 



A. N., Am. J. Physiol., 1924, 71, 209- 

 227, used micro-pipettes to remove 

 glomerular filtrate from the Bowman 

 spaces of frog Malphigian corpuscles. 

 This was a triumph of imagination, in- 

 sight, and technique. It initiated and 

 provided a firm foundation for the whole 

 modern series of studies of kidney func- 

 tion. The example set by Richards 

 and Wearn should not be lost or ignored. 

 Similar studies of samples from defined 

 micro-anatomical structures, taken dur- 

 ing defined phases of physiologic and 

 pathologic processes will undoubtedly 

 go a long way toward unravelling many 

 current and future problems. This 

 must be kept in mind as increasingly 

 sensitive and accurate methods are de- 

 vised for measuring the concentrations 

 of substances in very small samples of 

 rather dilute solutions. The use of 

 special isotopes (initiated by Hevesy) 

 is greatly increasing the abilities of 

 analysts to detect and measure sub- 

 stances in extremely small biological 

 samples. One next necessary step in 

 this growing branch of knowledge must 

 consist in defining and knowing the 

 micro-anatomical regions from which 

 each sample comes and the physiologic 

 or pathologic states under which each 

 sample is collected, as accurately as the 

 composition of the sample can now be 

 determined. This seems obvious; ob- 

 vious also is the fact that in many 

 quarters it seems not yet to be appre- 

 ciated. 



4. The method plus suitable and ade- 

 quate micro-dissection and micro-in- 

 jection techniques (Chambers, R. and 

 Kopac, M. J., in McClung, 2nd ed., pp. 

 62-109; Buchtal, F., Ztschr. f. Wis- 

 sensch. Mikr., 1942, 58, 126-133) should 

 make it possible to place samples of 

 various substances in defined micro- 

 anatomical areas, during defined phases 

 of physiologic or pathologic processes 

 and watch or otherwise determine the 

 responses of parts of living systems to 

 the newly arrived material. For an 

 extensive example of one such set of 

 studies, see Knisely, M. II., Bloch, 

 E. H., and Warner, L., cited above. 



5. The method permits the study of 

 some kinds of pathologic processes while 

 they are still in reversible stages, that 

 is, in controllable stages. Autopsies 

 and autopsy sections show the final 

 cumulative results of all of the simul- 

 taneous and consecutive pathologic and 

 reparative processes which had been 

 going on. That is, they show the pre- 

 servable, visible part of the accumu- 

 lated results after some one or more sets 

 of pathologic processes have become ir- 

 reversible. The microscopic studies of 

 living tissues allow examination of some 



