=138.= Experience has shown that the practice of making hasty and often formless records in the field is unwise and is apt to be inaccurate as well. The time saved in the field is more than counterbalanced by that consumed in copying the results into the permanent form. The danger of error in field notes rapidly taken is very grave, and the chance of confusion and the waste of time in deciphering them are great. Moreover, the task of checking a copy with the original, which is absolutely necessary for accuracy, involves a further expenditure of time and energy. For these reasons the field record should be made in permanent form. Definite record sheets are used, and the invariable rule is made that all readings are to be noted in ink at the time and spot where they are taken. On a long journey, or in the face of many observations, the tendency to take notes or to record observations rapidly is very great, but this will correct itself after a few attempts to use such notes. The record forms for various factors have been indicated in the proper place, as well as the one for simultaneous readings. Ecograph sheets are carefully filed, and constitute permanent records. With a little practice they may be read almost as easily as tables, and any attempt to put them into tabular form is a mere waste of time. For purposes of study and of publication, it often becomes necessary to bring together all the results obtained for a particular habitat, both by simple instruments and by ecographs. The form of record used for this is essentially that already indicated for simultaneous readings on page 92, since general features and constant factors can not well be included in the table. Record sheets of this type have been printed at a cost of $5 per thousand, and the various factor records can be obtained at about the same rate. The size of sheet used is 9½ × 7¾ inches. The record book is the usual notebook cover, which has been found neither too large nor too small. It is protected from dirt and rain by a covering of oilcloth which overlaps the edges. Record books should be carefully labeled, and each one should contain a single year’s records. _Factor Curves_